Fantasy is the driving element in the serial killer’s life, and as a result plays an integral role in the murder itself. The killer is not only pushed to kill by their thought patterns (Ressler, 1988) , but is essentially incited to murder by an intrusive fantasy life (Burgess, 1991). Their early-learned view that violence against other humans is a “normal” and “acceptable” (Holmes & De Burger, 1988) way of getting what they want serves to virtually encourage murder. And just as in addiction, their ambivalent views toward societal values encourage them to try a proscribed behavior, in this murdercase. Within the murder, there are many reflections of fantasy. Even among the serial killers who had little or no conscious plans of murder, there is still a great deal of evidence in their belief structures for unconscious fantasy (Ressler, 1988) . The murder, as a whole, is an integral part of the serial killer’s sexual fantasy (Brown, 1991) . And crime scenes tend to echo elements of the fantasy in such things as the condition of the body, the body’s state of dress and position, and the visibility of the disposal local (Ressler, 1988) . As the years pass, the future killer’s reliance on fantasy only increases. It continues to substitute for real feelings of control, and as a vent for anger, and also comes to compensate for feelings of low self-esteem and feelings of general failure (FBI, 1985) . As a result of their reliance on fantasy, and as a result of childhood abuse, the future killer has developed a series of negative personality traits which results in only increased isolation. These traits include a preference for autoerotic activity, aggression, chronic lying, rebelliousness, and a preference for fetish behavior (Ressler, 1988) . The killer’s initial difficulty in distinguishing between reality and fantasy continues to grow (Abrahamson, 1973) . Fueled by the negative personality traits, and inability to distinguish fantasy from reality, the future killer fails to adequately develop social relationships (Drukteinis, 1992) . The early isolation, leading to antisocial acts, is fueled by the acts, and increased isolation results. The isolation and antisocial behavior build into a feedback cycle, resulting in more violent behavior on the part of the killer, and even greater isolation from society. The lack of punishment resulting from the future killer’s violent behavior is a type of reinforcement (Ressler, 1988) . The killer’s childhood fantasies and thinking patterns stimulate only themselves, and while reducing tension, serve only to further their alienation ( Ressler, 1988) . The social isolation, the result of early antisocial behavior and fantasy, only increases the child’s reliance on fantasy (Ressler, 1988) . This isolation is reformed into even greater anger against society (Ressler, 1988) . The killer’s early reliance on fantasy leads to violent acts, and childhood abuse leads toward anger against society. Anger produces violent acts, which in turn increases the child’s isolation. The increased isolation leads to even more anger, antisocial acts, and a vastly increased dependence on fantasy. The self-feeding cycle of isolation, anger and fantasy only serves to catapult the future killer even farther away from what society views as normal, and even closer to the act of homicide. By the time of sexual development, and autoerotic experimentation, fantasy is well on its way to it’s final role, that of sole coping device. Man’s ability to rehearse and anticipate positive outcomes from his behavior, and ability to reinforce self through forethought and planning, through imagina- tion and fantasy (Orford, 1985) , is what has gone terribly wrong here. The serial killer, though outwardly secure and apparently stable, is in reality terribly insecure (Geberth, 1990) . When the killer is not in complete control of the situation, he feels helpless, without power. Fantasy, here, is like other forms of addiction, lending a form of temporary self-esteem. The extreme violence of some killers is entangled with this low self-esteem. Holmes & De Burger (1988) found a corre- lation between high levels of violence and low self-concept, especially among offenders of average and greater than average intelligence. Fantasy has become a situation in which the killer is always in control, always powerful. This fantasy has gone so far as to become another reality for the killer, equivalent to, and as viable as, the real world. Indeed, the fantasy world is so real to the killer, that he believes he can move between fantasy and reality, that there is no distinguishable difference (FBI, 1985) . Murder is not the isolated event which the media and public view it to be. Rather, it is the logical outgrowth, an extension, of the serial killer’s fantasy life. Fantasy is the drive mechanism for the murder (Brown, 1991) . And even though fantasy preceded murder, the act of murder has, in a sense, solidified the fantasy (FBI, 1985) . The serial killer’s great difficulty in differentiating between fantasy and reality has been pushed over the edge by the act of murder. The acting out of the fantasy has linked it with the real world, and in the serial killer’s mind, the fantasy has become reality (FBI, 1985) . In the words of the FBI (1985) : “the offender believes he can now control reality”. Essentially: “sexual homicide is an act of control, dominance and performance that is representative of an underlying fantasy embedded with violence, sexuality and death”. Though it is not immediately obvious in all cases, it is nonetheless true that the serial killer murders to preserve the fantasy (Ressler, 1988) . Often, the fantasy is of murder, and the only way to keep it alive is to act it out. The protection of the fantasy may have been required by a variety of factors, some of which are external, such as: an interruption by the victim of the offender’s feeling of dominance, or being enraged at the victim’s behavior (Ressler, 1988) . The murder is not recognized as such by the killer. Rather, most killers describe an “unbearable” (Holmes & De Burger, 1988) urge to kill. The net effect of this murder is to move the killer to a higher level of fantasy (FBI, 1985) . The serial killer experiences distinct psychological benefits from the murder, not the least of which is the relief from intense anxiety (Brown, 1991) . Indeed, this relief is not entirely dissimilar to the function of a compulsion (Brown, 1991) or an addiction. Stress is the triggering stimuli for most serial murders (Ressler, 1988) , much as stress can trigger drinking bouts in alcoholics. An interesting note is that some killers are so affected that they surrender to the authorities after the first or second murder. As a rule, however, the more the serial killer murders, the greater the psychological gain. The fantasies survive and are elaborated upon, and the behavior of the killer is reinforced. Just as fantasy and isolation fed each other, so the murder fuels the fantasy and the fantasy fuels the murder. The serial killer does not stop of his own accord. Unless prevented, the serial killer with kill again and again (Holmes & De Burger, 1988) . Each successful murder exhilarates the killer, both confirming and reinforcing the act. Simply put: serial killers tend to increase their killings it appears they have to kill often to maintain their equili- brium. The fantasy and psychic high that they obtain induces bold and more frequent attacks, sometimes with a complete disregard of risk (Geberth, 1990) . While each murder reinforces the fantasy, the fantasy grows. One murder is no longer enough; the killer must kill again, and as the killings grow, he begins to require them more often. The feelings of success of self-worth begin to stem from the killings only. All serial killers follow this pattern, increasing the fre- quency of their killings (US Congress, 1984) . By this time, there are no remaining internal forces that will stop the serial killer’s actions. The serial killer, rather than being a creature of complete and unutterable evil, as Geberth (1992) would argue, is in truth an addict. Shaped by a dysfunctional childhood and faulty learning, the serial killer learns to depend on fantasy as a coping mechanism. This is, in certain respects, no different from the alcoholic using their drink of choice as a coping mechanism. Just as addicts tend to fall into a downward spiral, until all else in their lives centers around the addictive substance, the serial killer’s life begins to revolve around fantasy. The revolution becomes so dominating that eventually fantasy becomes the center of the serial killer’s life. And just as the heroin addict’s need for a fix may drive him to steal, the serial killer’s obli- gation to the fantasy drives him to murder. In short, the cycle of the serial killer is no different from the cycle of any other addict, the end result of murder being functionally the same as the heroin addict’s theft.
In general, the theoretical perspective which provides the best explanation of a serial murder is that based on the systemic-relational model (Wilson & Seaman, 1990) . According to this explanation, the individual, taking into account one’s innate characteristics, is under the influence of the systems in which he is inserted and the relationships he has established with others in the environment. Scholars have also stressed the importance of the presence of traumatic experiences in childhood and adolescence of serial killers, defining them as the pro- duct of the family of origin and the parental background; this element unites the individual and any special physiological characteristics. If in the family and in society, relationships become negative and disruptive, the serial killer loses the sense of reality (Lavorino, 1993) . The homicidal action briefly reassembles the psychological system of the subject until other negative factors interfere. In light of this, serial homicidal behavior can be seen as the result of three factors (individual, social and environmental, relational), which are interwoven with each other, and change from one serial killer to another. The individual factor includes all the personal characteristics of a serial killer. The socio-environmental factor includes all the social components that can affect the behavior of a serial murderer. The relational factor is a synthesis of the other two factors and is their meeting point. This factor is a measure of the degree of exchange between the individual and the environment and the way in which the subject behaves with others (Vaillant, 1975) . In this field, there is the tendency of many authors to only consider serial killers as those individuals whose murders are, in some way, linked to sexual disorders (Douglas, Ressler, Burgess, & Hartman, 1986). In fact, a single explanation for all serial killers does not exist, because the reasons for serial homicidal behavior can be manifold. As regards the taxonomy of serial murder, it must be pointed out that there are multiple ways of classifying it. A serial murder is connected to the motive (Andreoli, 2004) , and focuses on the reason that prompted the subject to conduct serial homicide. Secondly, a serial murder classification can be made in relation to the number of people who are killed by a serial killer. Some serial killers commit their first murder individually, and subsequent murders in pairs or in groups (in this case, it refers to serial murders committed in variable numbers). Another classification criterion relates to the degree of planning the murder (Vronsky, 2004) : the homicidal behavior can swing between an absolute planning of all aspects of the crime and a total lack of organization, or the serial murderer can schedule only a few stages of the murder, which are considered most important in the realization of their ritual. Finally, some authors have identified various stages in serial homicidal behavior.
2. A Serial Killer’s Fantasy
When the serial killer murders his first victim, he activates what is known as “cyclical mechanism”, entering a circular complex mental process, like an addiction, which leads him to kill again (Bruno & Marrazzi, 2000) . The murder becomes, therefore, the transposition of one or more mental images within a real context and the dynamic process is bound to repeat itself with particular features of rituals (Musci, Poor, & Tavella, 1997) . The imagination is the fundamental element of the human psyche through which we can change reality, replace something, review the past and anticipate the future (Anderson, 1994) . This is most commonly used by adults, as much as children, to gain and maintain control over an imagined situation. It can be defined as the imaginative process by which a subject attempts to obtain substitute gratification, through activities experienced in the mind that he is not able to actually experience in reality (Douglas, 2000) . Through imagination, any mood, such as anger, for example, begins to take shape oriented toward a specific goal and a specific direction (Carlisle, 1993) . The elaboration of fantasy begins at an early age. During childhood children take refuge in fantasy and, according to the family context in which they grow up, project what they have learned or experienced as a way of relating to others. Living and growing up in a dysfunctional and hostile environment can generate psychological consequences for the child who will seek refuge in fantasy. The child will create a personal imaginary world and will project the hostility and hatred that the child has experienced in the real world. In fantasies any individual can imagine the self to be immense and without limits. The main difference between a criminal and a normal subject is that the former believes to have some sort of divine right to satisfy his fantasies, without moral or legal restrictions (Norris, 1988) . The serial killer’s imagination plays a major role as he begins to fantasize about acts to be performed in order to express dominance over another human being. The decision-making power of life and death infuses a feeling of omnipotence. He will live this fantasy compulsively and as individual scenes are revived, he will relive every single fragment and moment of madness as a unique and great experience which must inevitably be carried out. When his delusional fantasies reach a peak, it is time to enjoy his actions of the murder, until a new emotional necessity or compulsion leads him to kill again (De Luca, 2000) . For the serial murderer, the victim is like a checkers pawn to be manipulated at will in order to “win the game”. These individuals compensate for their social loneliness by retreating to their fantasy world, which is in fact dominated by their imagination. The more time spent fantasizing, the faster he will become dependent on the fantasies that feed the sense of self. At one point, he feels obliged to enact the fantasies, dominate the victims and transform them into objects to be used for his pleasure (Scott, 2000) . Any serial killer, regardless of the reason behind the murders, always begins his destructive path due to fantasies. The murder is “lived” obsessively through increasingly elaborate fantasies, fueled by intense and prolonged exposure to violent pornography (Skrapec, 1996) . This predisposition towards sexualised and aggressive fantasy is key in most serial killers, from childhood. In fact, a favorite recreational activity by serial killers from an early age is performing actions which transform into real aggressive fantasies that, progressively, have assumed a role of utmost importance within the psyche of the child. Early fantasies of a sexual and aggressive nature generate more and more violent behavioral episodes starting with the creation of violent fantasies on inanimate objects, then moving onto animals, until reaching the victimization of others who are considered human beings, yet they are mere objects whose function is to satisfy their fantasies (Bandura & Walters, 1959) .
Numerous studies have confirmed that most serial killers show a high proficiency-oriented view towards death and all that concerns it (such as serial killer: Pedro Alonso Lopez, Theodore Robert Bundy, Jefree Dahmer, Daniel Camargo Barbosa, Richard Ramirez, Henry Holmes, Harold Shipman). Confirmation of this view can be determined from the fact that when they are arrested, serial killers are often able to recount the dynamics of their crimes with a meticulous attention to detail, through visual memory (Meloy, 2000) . During the developmental period, the serial killer processes a highly developed system of fantasies to defend against a traumatic reality that he cannot accept. As an adult, the level of processing of fantasies allows him to relive the trauma suffered by reversing the roles; thus, in his mind he is no longer the passive victim, but becomes an active aggressor. This role reversal makes it possible to momentarily overcome the trauma through a virtual revenge situation. With the progression of the fantasies, the virtual world is no longer sufficient and the serial murderer needs to change the fantasy into reality (Boyle, 2005). For each serial murderer, fantasy is the central element of a murder (Hazelwood & Douglas, 1980) according to the following scheme: 1) relational: concerns the way in which the criminal fantasizes about establishing a relationship with the future victim. An extreme variant of an imagined relationship is the master/slave one, which is very exciting for the subject because it allows him to fully exercise his domination and control needs; 2) paraphilia: concerns the sexual sphere of the fantasy. The criminal acts almost always start from a set of sexual perversions which are a concrete expression of his inner fantasy world; 3) situational: represents that part of the fantasy with regards to the setting in which the criminal wants to carry out the murder and how he wishes to kill the victim. The subject can fantasize about building a “torture chamber”, and may wish to take the victim to a remote forest, or dress the victim in a certain way and let her pronounce certain words in order to increase the excitement. To implement this component, the ritual criminal becomes a director who organizes the crime scene at his will; 4) type of victim: the serial killer needs to choose a specific type of victim that reflects his fantasies as regards gender, age, race, complexion, and height; all those aspects that make the prey unique and irreplaceable in the killer’s mind. The attack is part of a ritual that allows the subject to find momentary relief from their internal tensions and the energy is channeled to the kind of victim that responds better to the needs of the criminal; 5) self-perception: the last component concerns the way in which the murderer is perceived within the fantasy. A serial killer can have a diversity of roles which can range from interpreting the feeling of complete inadequacy to a sense of divine omnipotence, through which he can exercise absolute control over another human being whom he cannot control in daily life.
3. Serial Killers: Thought Patterns and Actions
From the many studies carried out in this field, it was possible to identify a serial killer’s thought pattern and action, which is divided into five phases that are repeated in a circular process (Ciappi, 1998) : 1) distorted thinking phase: it is the psychological stage common to all serial killers. The subject is unable to properly assess the impact of a deviant act, as he fails to consider the consequences and is more interested in the emotional gratification that can result from his actions; 2) motivational phase: a single event or set of events, which are real or imagined, because of the transition to this stage. The stimulus is perceived as something personal, and the distorted mentality of the subject produces a disproportionate response to incidents. The subject, in fact, feels the need to physically offload, and begins the process of hunting his prey/victim; 3) inner negative answer phase: at this point the murderer has to deal with feelings of inadequacy, especially when there are negative messages from the society that surrounds him. He needs to strengthen his unstable sense of identity and does so using the means he knows best: domination, control and violence; 4) external negative response phase: This element helps the subject to confirm his superiority as a person. There is no kind of interest in the possible consequences of his criminal actions. The behavior has the objective of increasing and stabilizing the sense of power; 5) restoration phase: This phase restores the balance that the subject had at the beginning of the process. Once back in this state of mind, the serial killer reflects on previously ignored dangerous consequences, realizing that his technique needs to be improved by choosing the victims properly, and dealing with where to leave the bodies so that they are found easily. The killer also thinks about how to minimize personal risks in upcoming murders. The subject, therefore, completes the cycle and returns to the “distorted thinking” phase.
4. Serial Killers: Biological Predispositions
Ordinary people often wonder about the nature of unconceivable and horrific actions that are committed by serial killers. It is important to clarify the origins of a serial killer (Giannangelo, 1996) . The interpretation of the three-phase model which was developed can answer these questions. Some individuals show a biological predisposition to violence due to deficits of the brain system which involve a low level of frustration tolerance. In this volatile brain structure, stressful events and environmental traumas are added (Tables 1-3).
The pathological personality has no adaptive capacity, so the subject is not able to face up to everyday problems posed by the real world, therefore he prefers to retreat into a private world of fantasies which satisfy him. Consequently, the real world only remains for the serial killer’s criminal activity, which he has previously fantasized about and that has led him to commit his first murder (Table 2).
After having committed murder, the killer is ready to start the destructive cycle and become a serial killer. Sooner or later, in fact, he feels a new impulse to kill. He chooses the victim, and after the murder, spends a period of relative calm in which he elaborates and relives the murder he has just committed in his fantasy, until, once more, imagination is not enough, and he will feel the need to kill again (Table 3).
The result is the development of an individual who suffers from low self- esteem leading to inability to create authentic and empathic personal relationships (Lachmann & Lachmann, 1995) . The central feature is poor control of impulses, which serve to stabilize the precarious sense of self through some superficial gratification. At the same time, they also develop sexual dysfunctions, which may
take the form of real perversions and make any relationship marked by real intimacy impossible (Roncagalli, 2016) .
5. Sequential Predatory Behavior
The serial killer’s behavior is usually characterized by several factors, which, in combination, give origin to homicidal actions, which arise cyclically in time. Sequential predatory behavior (Holmes & Holmes, 1998) , is developed through the interaction of four key elements: 1) imagination: is the element which is the basis of despised sexuality and is part of a serial predator’s personality. With a series of murders, the fantasy becomes more sexual and more aggressive and the subject develops a form of dependency on it; 2) symbolism: The sexual perversions of serial killers have a strong symbolic value. In particular, the collection of fetish items immediately after the murder serves to remind the killer of the victim, feed the fantasies and get emotional gratification. Serial murder is a form of communication used by the serial killer, in which the expressive function is to “show” sides of the killer’s personality and send a conscious message through the only language known by the subject; 3) ritualism: a peculiar element of serial murder is that of ritual. The subject is forced by his internal fantasies to follow a constant repetitive pattern over time in some or all of its phases; for example, the choice of the same type of victim, and the arrangement of the corpse always in a certain way. The subject is obliged to respect a certain ritual order which is necessary to represent his inner world in real life; 4) compulsion: as in any type of addiction, the need to do evil is an expression of an inner need, first psychological, and then physiological. Therefore, this is a compulsive behavior fueled by impossible desires. With the passage of time, and the progression of homicides, he develops a true syndrome of habituation and addiction that leads the subject to always seek higher levels of violence.
1) Motivational phase
The motives represent the source of a serial killer’s behavior. They are divided into: a) primary motivations, common to all individuals and especially related to physiological needs; b) secondary motivations, which include all those complex behaviors, sometimes socially determined and not related to physiological needs. The motivational drive concerns some psychological dynamics which affect: perception on the part of the subject that the environment does not care for him; an obsessive search for attention, positive reinforcement, gratification; the desire to possess and control the environment and other general control; the transformation of the need to possess and control sexual impulses and the need to kill to affect the environment which he perceives as “bad” in order to counterbalance all his frustrations with one single action.
2) Criminal fantasy phase
In the mind of the subject the materialization of a fantasy occurs. In the absence of a criminal imagination the path is blocked and the crime cannot be committed. A serial killer dreams of killing and raping, and of having power over other people’s lives, almost as if, by controlling the lives of victims, he could regain control over his life. Sex and a violent sadistic sexual fantasy play a major role because the sexual sphere is the most exciting aspect for the serial killer and the most derogatory to the victim.
3) Mental anticipation of the effects phase
A serial killer mentally anticipates the effects of his actions. The effects may have instrumental functions (e.g. murder to have control) or expressive functions (e.g. murder to strengthen self-esteem and self-efficacy). The first function acts on the second, directing it; in every crime the weight of one or the other function may be different, but they are both present. The serial killer mentally anticipates “the atmosphere of aggression” with the aim of reducing the sense of existential angst.
4) The design phase
In this phase the subject evaluates the convenience of criminal action through a decision-making process (pro-counterbalance). Making the selection, the behavior is programmed in all its variables and the subject decides whether, how and when, to take that action. During the design phase, the subject can see the difficulty of carrying out the crime and decide to stop or postpone the murderous conduct.
5) Execution phase
The subject applies the strategies outlined in the planning phase. When he murders, it is the culmination of excitement, the moment when he can triumph, dominate, and denigrate another human being. This phase produces internal sensations to the subject, both positive and negative, which will affect the possibility of a recurrence of homicidal behavior.
6) Satisfaction after killing
This is the stage in which the subject feels satisfied. Recurrence of violent behavior depends on the presence and degree of certain factors: 1) experiences during the first murder and subsequent learning mechanism stimulus/response; 2) if a single murder has satisfied the sense of inadequacy and frustration, as well as the need to control; 3) elaboration of emotions experienced during the murder after a certain period; 4) stimulation coming from amplification by the media of the killer; 5) further frustrating stimulation from the killer’s social environment.
The role of the media is very important in strengthening the homicidal fantasies. The media have the ability to make the subject feel important by increasing his “elusive” image.
6. The Time of the Murder: The Execution Phase
The executive phase (Norris, 1988) , consists of some phases, each of which is correlated to a particular mental state: 1) auroral phase: characterized by a dissociative state, in which the killer has crossed the borders that separate imagination from reality. It can last days, months or even years. The phase of repetitions and elaborations of fantasies have themes such as murder, revenge, control, mutilation, cannibalism and possession. Nothing can stop the murderer at this stage; 2) the phase of identifying the victim: the serial killer begins to attend places where it is more likely for him to find a victim. There is nothing random or accidental at this stage. Every serial killer has a definite “list” for the kind of victim he needs to satisfy his fantasies; 3) the seduction phase: the serial killer patiently lures, fascinates, persuades and woos his victim into a vulnerable position so that he can implement his murder. He begins a very seemingly innocent conversation, whose real intention is to get the vital information needed to lure the victim into a trap. Individuals are charismatic, kind, charming, and well- dressed. The serial killer tries to “make himself known” to the victim. When he gains the victim’s trust, he moves onto the next phase; 4) the capture phase: usually, the killer acts when the victim is alone, in an isolated place. The previous phases have the task of increasing the degree of excitation of the subject; the capture causes pleasure, as the murderer feels that the victim is, at last, in his possession, and he can take all the time he wants to prepare the murderous ritual. The capture can be swift and decisive, so as not to give the victim a chance, but it can also be slow and studied, in order to increase the terror level of his prey. Once the killer is sure that there is no way for the victim to escape, he reveals his true intentions; 5) the murder phase: the killer’s fantasies are enacted. It is the stage of triumph, often accompanied by an orgasmic release of tension built up in the previous steps. Each murderer has his own way of killing, and that is what gives him greater satisfaction; 6) the depersonalization phase: the victim’s face is often covered, and the victim is thereby “depersonalized”. Rape or mutilation often takes place after the victim was rendered unconscious, is dying or is already dead. Sexual acts often involve insertion of foreign objects into body orifices (insertional necrophilia). Death is caused by strangulation, wounds from blunt or sharp weapons, and the weapon is often found at the crime scene; 7) totemic phase: it is the time following the crime, when the aggressor relives the murder committed through memories and fetishes. The experience was so rewarding that the killer feels drained of all energy. To prolong the feeling of power and triumph, the murderer takes souvenirs or crime trophies (body parts, clothing). These trophies are essential in order to create and maintain in some way, a bridge between his fantasies and the crimes committed. The murderer can pose the corpse. This phase also practices various perversions, such as cannibalism, necrophilia, and masturbation in front of the body or parts of the body. An organized killer is more inclined to take photographs or video the victim, both before and after the murder; 8) depressive phase: after the murder, the serial killer suffers great emotional disappointment and he gets depressed.
However, since the victims are seen as objects, the memory of the murders may fade over time, and shift the killers in their fantasies, make them move towards a new murder, and restart the homicidal cycle (Samenow, 1984) .
7. Serial Killers and Socio-Environmental Factors
Serial homicidal behavior is the product of the circular combination of three factors (F) which are interwoven with each other, with variable importance from individual to individual, and of different intensities of the respective sub-factors (SF). The initials of the three factors: Social and environmental (S), Individual (I) and Relational (R) identify the SIR model, which constitutes the starting point for creating a new taxonomy of serial murder that takes into account the real complexity of the phenomenon and that can explain why a person becomes serial killer (De Luca & Mastronardi, 2011) . The F factor (S) includes all social and environmental components that can affect the behavior of a serial murderer.
1) The socio-environmental factor
SF1: Original family environment. In most cases, the family in which a serial killer grows up does not allow a healthy development of empathy and, consequently, the formation of a balanced personality. Physical, sexual and psychological abuse, and emotional deprivation are some of the many traumas which the subject undergoes during childhood that establish the foundations for future criminal behavior.
SF2: Insertion in society. During adolescence, and, later, as an adult, a serial murderer has, in principle, a low level of inclusion in society; in fact, very often, he does not have a rewarding job and has few friends, and is a person with few cultural interests. Even in those cases where, apparently, the subject shows a “facade of normality” (for example, is married, has children, a stable job and is considered positively by the community in which he lives), in reality it is an inclusion which stops at a superficial level and does not involve the core of the personality, haunted by deep inner anxieties.
SF3: Predisposing, facilitating and triggering events. In every life story of a serial killer, you can find predisposing, facilitating and triggering events that may occur at any time, triggering the homicidal chain reaction; these events, which for another person may seem completely harmless, instead, for a serial murderer have a disruptive emotional energy, which is able to shatter a fragile identity. The list of these events is not the same for everyone, but among the most common, there are sudden deaths, which upset the precarious internal balance of the subject, sudden abandonment by a person, easy access to a weapon, and the presence of a certain type of easily approachable victim.
SF4: Sub-cultural influences. This factor assumes considerable importance in those cases in which the serial killer grows up in a criminal environment, where, for example, the parents exhibit criminal behavior, or the subject is inserted, especially during adolescence, in a group of criminal peers who exercise a significant influence over him. Several serial killers start a criminal career early, because they are included in a context that facilitates and supports the shift to an aggressive action.
SF5: Rewards and punishments by the environment. The way society reacts to the first deviant and criminal acts by a potential serial killer plays an important role in guiding the future behavior of the subject. The criminal path of an individual does not begin with a serial murder, but with less serious incidents. The subject may receive rewards or punishments for their actions, or a punishment with an educational function, which can serve to slow or block the evolution of serial homicidal behavior.
2) The individual factor
SF1: Psychological and psychopathological traits. A serial killer has peculiar psychological characteristics that, in many cases, are related to psychopathological traits and can take different forms (mental illness, neurological deficits) and orientate his behavior. In some subjects, a “predisposition to evil” seems to exist with very early criminal behavior, even in families where there is no presence of trauma.
SF2: Sexuality. The quality and quantity of sexual impulses of the subject during the developmental period feeds their fantasy life and is a key determinant of adult behavior. The development of a perverse sexuality can be a central component of a future serial killer.
SF3: Imaginative Life (fantasies). A common feature of all serial killers is to have a very rich and varied imaginative life. Compared to the fantasies of normal individuals, those of potential serial killers are oriented early on the domain, control and destruction of other people who are imagined as “objects” at disposal for personal gratification.
SF4: Subjective needs (motivations). Throughout life, everyone has aspirations and motivations that lead them to exhibit certain behaviors. In serial killers, murder is always linked to purely personal psychological motivations; in fact, when they are captured and interrogated about what prompted them to kill, it is very difficult to understand their justification.
SF5: Processing capacity of trauma. This individual factor is very important to understand why some people become serial killers and others do not, even though there are similar life experiences in their personal history. A traumatic event (for example, the mourning of a loved one, humiliation caused by schoolmates, rejection by a sexual partner) can be handled in different ways by different people.
3) The relational factor
SF1: Communication with himself. Serial murderers have difficulty establishing and maintaining genuinely empathic relationships with others and prefer to live in a dimension of loneliness, accompanied only by their imaginations. The quality of these fantasies and the internal dialogue that every serial killer has with himself, are of fundamental importance and influence his future action.
SF2: Communication of the individual-family of origin. The devaluing attitude of a father or a mother could irreversibly compromise the development of a child’s personality. Indeed, tensions with parents can determine future adult behavior, which can also lead them to kill women “that remind them of their mother” because, despite not having the courage to murder their own mother, they murder her symbolically by using other victims.
SF3: Communication of the individual-sexual partners. Sex is one of the fundamental aspects of human life and the type of interaction created by the individual with sexual partners has definite influence on his personality. Many of the serial killers analyzed, have developed an inadequate path composed of refusal, abandonment and humiliation of every kind. Therefore, they come to hate a certain category of people (in most cases, women) against whom they wish to take revenge by killing them.
SF4: Communication of the individual-society. Some serial killers manage to camouflage themselves behind a mask of normality by opening very superficial relationships with other social subjects, but, in fact, continue to treat people as mere “objects” and do not believe that it is possible to establish a positive relationship. In the event that serial murderers have their own family (maybe married with children), the relationship with the family has the same trend as the external ones: a “facade of normality”, while, in reality, domestic life is marked by a daily underlying tension.
SF5: Ways of learning violence. From what we can deduce, a human being is not born a serial killer, but, over the years, learns the use of violence to satisfy his needs (identity, sexual, personal gratification, omnipotence) and ways of learning are always a question of interaction with one or more negative patterns taken as reference points (Table 4).
Analyzing the phenomenon of serial killers, elements emerge which can determine serial homicidal behavior. The instinct of repulsion of death, which is present in all human beings, is weakened or absent in serial killers. They feel attracted to death, and all that concerns death. Fantasy has a fundamental role and pushes the serial killer into an imaginary world, where he finds more satisfaction than in the real world. Before killing, he will experiment the murder in his imagination. If he is satisfied by the first fantasy, he will create other fantasies, until,
at a certain point, dissatisfaction will lead him to re-enter the real world to apply three essential elements: power, control and domain. On termination of this phase, he will fantasize about a new victim to sacrifice. This research cannot provide definitive answers to the problem about serial murderer, however, it can be useful for further research in the field of serial killers.
 Douglas, J. E., Ressler, R. K., Burgess, E. W., & Hartman, C. R. (1986). Criminal Profiling from Crime Scene Analysis. Behavioural Sciences and the Law, 4, 401-421.
 Lachmann, A., & Lachmann, F. M. (1995). The Personification of Evil: Motivations and Fantasies of the Serial Killer. International Forum of Psychoanalysis, 4, 17-23.
 Scott, S., & Westley A. D. (2000). Diary of a Child Predator.
 US Congress (1984). Serial Murders: Hearing before the Subcommittee of Juvenile Justice of the Committee on the Judiciary US Senate. Patterns of Murders Committed by One Person, in Large Numbers with No Apparent Rhyme, Reason or Motivation, Washington: US Government.