The Classification of Sex-Related Homicides

By Vernon J. Geberth, M.S., M.P.S.
Former Commander, Bronx Homicide, NYPD

©1996 Vernon J. Geberth, Practical Homicide Investigation

Return to Research Materials


Sex related homicides include rape-murders, serial murders, killings which involve both anal and oral sodomy, and other acts of sexual perversion as well as sexually oriented interpersonal violence cases.

A homicide is classified as "sex-related" when there is evidence of sexual activity observed in the crime scene or upon the body of the victim. This includes:

  1. The type of, or lack of attire on the victim.
  2. Evidence of seminal fluid on, near, or in the body.
  3. Evidence of sexual injury and/or sexual mutilation.
  4. Sexualized positioning of the body.
  5. Evidence of substitute sexual activity, i.e. fantasy, ritualism, symbolism and/or masturbation.
  6. Multiple stabbing or cuttings to the body. This includes slicing wounds across the abdomen of the victim, throat slashing and over-kill type injuries which are considered highly suggestive of a sexual motivation.

The victims of these crimes are usually females and young children, and the killer a male. However, it is important to note that sex related homicides involve homosexual as well as heterosexual relationships. The homicide might have sexual implications even without an overt sex act or observable sexual activity at the crime scene. It is important to note that unlike other murders, the motive or reason for the killing may not always be readily discernable or as "clear-cut" as is presented in a robbery-homicide, a drug related murder, or an organized crime "hit". Practically speaking, if the body is that of a female, and it is found nude or partially clothed, the investigator should think "sex crime."

In sex related homicide cases, basic evidence collection procedures acquire an increased importance. Human behavior patterns and psychosexual activities, not generally amenable to ordinary collection techniques become additional factors to consider in determining the reason and motive for the killing. Practical experience in homicide investigation coupled with an understanding of human behavior patterns and human sexuality are important prerequisites in analyzing these types of cases.


The three components of the human sex drive are biological (instinctive), physiological (functional), and emotional (mental). The emotional component is the manifestation of the culmination of our psychosexual development. According to experts, the psychosexual or emotional component is the strongest of the three, accounting for approximately 70% of the human sex drive.

Essentially, our human sexuality is established during our psychosexual development through conditioning, adjustment and experience, which involves both nature and nurture. Sexual behaviors are learned behaviors infused with emotion in which the individual develops a perception of what is sexually satisfying and what is socially appropriate within the context of his or her environment.

Clinically speaking, there is a behavioral distinctiveness in human sexuality. This unique aspect of our arousal and response system accounts for why individuals differ in their sexual behaviors and show selectivity in choosing their mates or sexual partners. Human sexuality is no longer simply instinctive but is based upon learned patterns of attraction, activity and fulfillment. Our sexual arousal and response system is effected by hormones, the brain's capacity to recall pleasurable experiences, fantasies, emotions, various sensory processes and the level of intimacy between two people. Sex is also a sensory act, involving the five senses of touch, sight, sound, smell, and taste. Each of our five senses is employed to a greater or lessor degree in our sexuality. For example, the sight of a scantily clothed woman might be an arousal factor for a man. Or, the sense of touch as it relates to a tender caress might be the stimulus that serves as an arousal factor for a woman.

These are perfectly appropriate responses as they relate to human sexuality because they are viewed as acceptable behaviors. However, persons who are inhibited sexually may develop unconventional forms of sexual expression. The person, who becomes aroused looking at the scantily clad woman might become obsessed with this sensory "turn-on". A deviance might then begin to emerge in a sexual behavior that becomes compulsive such as in the paraphilia voyeurism.

Sexual behaviors are classified as either acceptable or unacceptable. This determination is based upon statistical, cultural, religious and subjective considerations. The subjective determination of what is sexually pleasing to the individual could be and many times is in conflict with the acceptable standards determined by the majority, which is statistical, cultural considerations, or religious influence. This does not prevent the individual from expressing his or her sexual needs. According to experts the sex drive is extremely powerful. The sexual drive is capable of overriding all the most severe social sanctions and/or penalties. Thus we see variant sexual needs frequently erupting into variant sexual behaviors.

These variations are divided into two groupings. The distinction between the categories is based on social effect. Does the activity infringe on the public welfare? Or is the activity a victimless sexual variant.

It also is the basis for an important investigative concept, which we in homicide investigation refer to as the "signature aspect" of the offender.

(See LAW and ORDER, November, 1995 "The Signature Aspect in Criminal Profiling."


An extremely important aspect of homicide investigation is the determination of the motive for the killing. In the sex-related homicide, there are a number of possibilities to consider. Sex related homicides include rape-murders, serial murders, killings which involve anal and oral sodomy and other acts of sexual perversion, as well as interpersonal violence scenarios.

A careful search should always be conducted at the crime scene and within the surrounding area for evidence of sexual activity. This includes the presence of sexual assault activity as well as substitute and paraphiliac behaviors. This evidence may be seminal fluid in the vagina, mouth, nasal area, or rectum. Or, there may be semen and other evidence discovered outside the body or upon the clothing. There may be pornographic books, videos, magazines and/or photographs found at the crime scene. The photographs may depict the victim involved in sexual activity. Or, there may be writings or messages left by the offender at the crime scene and/or upon the body of the deceased. In any event, these factors are important in determining what type of sexual activity that may have taken place.

Human behavior, although unpredictable, is oftentimes repetitive. Research has indicated that certain actions engaged in at the homicide crime scene by certain types of personalities will repeat themselves in other homicide investigations. The homicide detective, who has enhanced his experience with a comprehension of the psychodynamics of human behavior will be able to develop a base of knowledge which can be applied to the investigation.

The reason and motivation for the crime is an extremely important consideration in establishing the investigative direction. "Was the murder the result of a lover's quarrel? Is the case attributed to interpersonal violence? Does it appear the victim was killed during a rape or sodomy attempt? Is the killing sexually oriented? Is there a psychotic motive, which sometimes appears to be motiveless or bizarre? Or, is the homicide the work of a sexual psychopath, with sadistic or impulsive implications? Each of these scenarios suggests a specific course of action.

However, in sex related homicide investigations the motivation behind the killing may not be immediately ascertained. There are any number of questions which can be asked and answered depending upon the circumstances and/or scenario of the crime scene. Consequently, an important factor in the proper formulation of an hypothesis will be the experience and knowledge of the investigator assigned to the case.

Examining a crime scene with the purpose of identifying and interpreting certain items which may serve as clues to the type of personality is an excellent technique. There are common denominators between the psychological make-up of the criminal and the psychological clues the crime scene reveals.


In my professional opinion, as an expert in the sphere of homicide investigation, sex related homicides can be classified into four distinct categories based upon frequency of occurrence.

  1. Interpersonal violence oriented disputes and assaults
  2. Rape and/or sodomy oriented assault
  3. Deviant oriented assault commonly referred to as a lust murder or psychotic killing (in these situations the motive for the murder is not readily discernible.)
  4. The serial murder

I have listed these four categories by their frequency of occurrence.

The most common type of sex related homicide originates from interpersonal violence. "Sexual domestic disputes" involve husbands and wives, men and women, boyfriends and girlfriends, boyfriends and boyfriends, girlfriends and girlfriends and even on occasion siblings. They may also involve third party relationships, such as "love triangles" former husbands and/or wives, and jilted lovers.

In some instances the death may not appear to be sexually motivated. However, upon an examination into the background and relationships of the victim a new possibility soon presents itself to the authorities. The motive in this category of slayings is most often based upon elements of rage, hate, anger, jealously or revenge.

The psychological dynamics involved in such violent interpersonal disputes and assaults oftentimes present scenarios which involve violent actions and statements such as, "If I can't have you then nobody will have you." This is most common in sexual domestic dispute cases.

The rape and/or sodomy motivation occurs when the offender's primary intent is to rape and/or sodomize the victim. The offense may be heterosexual or homosexual depending on the circumstances of the crime. These homicides occur under the following circumstances:

  1. The assailant has used excessive force in overcoming the resistance of the victim and/or furthering the sexual assault.
  2. The death is intentional because the assailant is known to the victim. The assailant kills to prevent the victim from identifying him.

These cases are extremely brutal, and death usually results from the assailant overcoming the resistance of the victim to the rape, sodomy, or homosexual assault. The victim may be choked or strangled into submission, or the mouth and nose may be held tightly in order to stifle the victim's screams, thereby causing asphyxia.

Blunt force injuries may be present when the killer has attempted to beat the victim into submission. In addition to the brutality of the attack a victim may also die of shock or other trauma. This is especially evident in young children or older persons.

The Deviant oriented assault or Lust murder is usually committed by someone who is defined as a lust murderer. Lust Murders are premeditated in the obsessive fantasies of the offender.

A psychological view of the development and effects of deviant fantasies and behaviors can be found in the psychosexual disorders, specifically the paraphilias IN DSM-IV.

The lust murderer is oriented towards deviant and sexually sadistic assault and is distinguished from other sex related homicide offenders by his involvement in mutilation of the victim. Lust murderers can be organized or disorganized. According to studies conducted by the FBI, most of these offenders are disorganized and do not engage in penis penetration of the victim. Instead, they may masturbate upon their victims and engage in post mortem mutilation. There may be displacement of the breasts of females (Defeminization), post mortem attack of the genitalia of males and females, evisceration, the insertion of objects into the body cavities of victims and sometimes anthropophagy, which is the consumption of human flesh and blood.

However, in the case of an organized lust murderer, there will be penis assault as well as other varied acts inflicted on the victim. The cutting and overkill type wound structures will be directed towards those parts of the body that the offender finds sexually significant to him.

Serial Killers, are extremely manipulative. Oftentimes, they are able to talk their victim into what has been described as their "comfort zone." This is a location where they feel comfortable and safe and can control the victim. Many times they use a ruse to gain access to a potential victim. Ted Bundy used a cast on his arm. John Wayne Gacy offered young men jobs in his construction business. Bittaker and Norris as well as others offered hitchhikers a lift, or as in the case of Christopher Wilder, posed as a talent scout, and offered modeling assignments, Bianchi and Bouno as well as others have posed as police officers, etc. They continually perfect their ruse and seem to have an uncanny knack at recognizing potential victims. They are quickly able to gain the victim's confidence with their verbal skills.

According to the original F.B.I. definition, "Serial murder was the killing of three or more separate victims with emotional time breaks between the killings."

The definition of serial murder, according to Practical Homicide Investigation is, "two or more separate murders where an individual, acting alone or with another, commits multiple homicides over a period of time, with time breaks between each murder event.

It should be noted that the FBI has since changed their definition of serial murder to two or more, since their earlier publications.

These breaks or "Cooling-off" periods range from days to weeks or months between victims.

In the case of the psychopathic killer, who is a serial murderer, I would suggest based upon my personal experience and research into these type offenders, that he kills because he likes to kill. These killers have premeditated, detailed plans for murder. Often these plans are improved upon with each successive killing; each new experience gives the offender insight into his next murder. I consulted one case in which the killer cruised a local strip for three hours and put over 120 miles on his van while searching for a victim. They target a certain type of victim. Someone who is vulnerable and easy to control. Their victims are males and females. They may select children, vagrants, prostitutes, or homosexuals. If the victim is a female, she may resemble other female victims in some aspect. (long hair, brunette, or redhead, coed, nurse, waitress, female executive, etc.)

Many serial killers have a fascination for police procedure. Some have even worked as police officers, reserve officers, or security guards. They use this experience to avoid detection. They have been known to frequent police hangouts and eavesdrop on police conversations during a case. They may even interject themselves into the investigation or offer to assist authorities in some manner which will avail them an opportunity to monitor the investigation.

The serial killer tends to increase his killings. These frequent attacks occur with a complete disregard of risk. Consequently, many of the country's most notorious serial killers were caught either by accident or during some independent police action not related to the murder investigation. New York Serial Killer Joel Rifkin, who was responsible for the murder of eighteen young women, most of whom were prostitutes, was apprehended by two alert New York State troopers on routine patrol. They observed Mr. Rifkin's vehicle operating without headlights and missing a rear license plate. He attempted to flee. However, when the troopers captured him they found the rotting corpse of one of his victims in the rear of his truck.


The criminal investigator confronted with a sex related homicide investigation should first address basic crime scene techniques. He or she should concentrate on the total documentation and preservation of the scene including those factors which suggest the possible psychodynamics of the event.

Remember the four classifications of sex related.

These categories will usually provide you with specific law enforcement strategies which can be applied to the investigation upon identification of the motive. An example would be, computer analysis of similar offenses, VI-CAP, utilizing a State-wide or Regional Information System or simply a recanvass of the neighborhood wherein the crime took place. Remember; that within each of the categories there exist elements of human behavior, human sexuality and possible sexual deviance. In any event, there aren't any simple clues, solutions or explanations which account for the logic of a person who commits a sex related homicide.

"We work for God."®