Serial Killers (World of Forensic Science)
Serial killers, those who kill more than once, pose a special problem for crime investigators because the their motives are often far less obvious than those of the person who commits a single homicide. Investigators describe three types of killer who commit multiple murders. The mass murderer kills several people at one time. Often these killers turn out to be disgruntled employees who show up at their places of work with shotgun in hand, bent on revenge. Spree killers often go on rampages with knives or guns, killing one person after another. Such people often have serious mental health problems. The serial killer, however, dispatches one victim at a time, with a time interval that may be as long as several years between each murder.
The "Washington Sniper" (aka, "Beltway Sniper" or "D.C. Sniper") killed ten people within a three-week period in the Washington, D.C., area in 2002. Originally thought to be a lone gunman, the killers turned out to be Gulf War veteran John Allen Muhammad and 18-year-old Lee Boyd Malvo, who were both convicted of capital murder. The media quickly labeled them "spree killers." Forensically speaking, however, they are probably more accurately described as a serial killers.
The serial killer tends to prey upon people at random. Usually, the attacker does not know the victims personally. The Federal Bureau of Investigation (FBI) Behavioral Science Unit developed the concept of psychological profiling in the 1960s to aid in the pursuit of serial killers and to let police know what kind of man (serial killers are nearly always men) is instigating the crimes.
Despite attempts by authorities to profile and find serial killers, some killers can continue killing and elude authorities for years. The so-called Green River Killer murdered at least 48 victims over a span of 16 years, from 1982 to 1998. The confessed murderer, Gary Leon Ridgway (now serving a life sentence), claimed that strangling young women was his "career."
Despite all the work that has been done on the psychology of the serial killer, forensic psychologists and psychiatrists are still far from understanding such people. Although it may be easier to comprehend someone who kills out of greed or revenge, the work of a serial killer is so far removed from normal behavior that most people have little understanding of his motives.
Many serial killers are psychopaths. Psychopathy, or anti-social personality disorder, is not considered completely curable. There is even debate by some scientists as to whether it is a mental illness at all. The hallmark of the psychopath is an extreme lack of guilt or empathy for others, which means the serial killer can carry out terrible crimes without emotional distress. Studies of serial killers in prison and evidence gathered from those who know them suggest that many of these murderers were the targets of physical, psychological, or sexual abuse in early childhood. This may lead them to build a world based on fantasy as a protective measure. These fantasies are then acted out in the course of a violent crime, often with a sexual context. The killer feels satisfied after the crime and then relaxes for a while. However, it is only a matter of time before the fantasies push them toward the next killing.
As the homicides mount, it becomes increasingly urgent for police to track down the killer. Also, as the killings mount, so too does the evidence, no matter how clever the killer may consider himself to be. As he continues, he may become careless or complacent, and the chances of his capture increase.
The forensic psychiatrist uses evidence from the crime scene to build a psychological profile of the serial killer. One categorization that has been found useful is to decide whether the investigators are dealing with an organized or a disorganized killer. If the crime scene suggests the murder was carefully planned and executed, then the killer may be a man of average to high intelligence who has a stable social network. He may be married with a family. He may also be employed. Living a "normal" life on the surface requires a degree of self-control, which manifests itself in the way the crime is carried out. Sometimes, though, the organized offender does lose control in the actual attack when the fantasy motivation takes over. In such cases, a violent or frenzied attack may occur, yet there may also be careful attempts to conceal or destroy evidence.
The disorganized offender leaves a mess at the crime scene. He may use any weapon that is available to strike out and makes little effort to cover his tracks. This lack of planning and control often suggests low intelligence. He is likely to be unemployed and may be a bit of a loner with few friends. The attack may be marked by excessive violence and could also include sexual contact with the victim after death. The disorganized serial killer often turns out to have a history of mental illness.
A number of other factors can be added to the profile. Many serial killers are young adults in their twenties or thirties. They tend not to cross racial lines. White killers tend to kill white victims; black killers tend to kill blacks. Many kill close to home the first few times, but then start to move farther away. Serial killers are eventually often highly mobile, which can make the logistics of catching them difficult.
Of particular interest to those investigating serial killers is what is taken from the scene or from the victim. In most crimes, the perpetrator will take items of monetary value, like cash or jewelry. They may also take evidence, such as a weapon. The serial killer often takes something known as a trophy or souvenir, of no obvious value except to him in his fantasy world. The item is known as a trophy if it is seen as a symbol of achievement and a souvenir if it is to remind the killer of the crime.
Trophies and souvenirs are an important part of the killer's modus operandi ("method of operation," or M.O.), the name given to the particular tools and strategies that distinguish the killer's work. The M.O. includes factors such as the location of the crimes, the tools used, the time of day, the alibi, and any accomplices involved. The M.O. may, of course, evolve over time as the killer becomes more experienced. The investigators will be particularly interested in any details that are unique to that killer, such as leaving a note behind. They will also look for the signature of the crime. Trophies and souvenirs can be part of the signature, as can mutilating or having sex with the corpse, or placing the body in a certain position.
Victimology, the study of the victim, can be crucial in tracking down a serial killer. The investigators need to know what it was about that particular person that attracted the killer. Was the victim truly chosen at random or had the person been stalked previously? The killer may have been searching for the one person who fit his fantasy and, if a common link can be found between the victims, this may be very revealing. For instance, nearly all of the victims of serial killer Ted Bundy had dark hair parted in the center.
The location of the serial killer's crimes is also of significance. Geographical profiling is based on the premise that the killer will operate in a zone where he feels comfortable. This may be near home or, alternatively, far away from it, depending on his psychological make-up. Location is not just where the crime was committed, but is also where the victim was abducted and where the body was taken and left after the crime. Establishing a geographical profile can be challenging if the victim was a prostitute, for instance, or someone who might not be missed by relatives or co-workers for a while. The Yorkshire Ripper killed several prostitutes in the United Kingdom from 1977 to 1981, and the difficulty of tracking the victims' movements sometimes hindered the investigation. Sometimes bodies are dumped in remote places and may not be found for some time. In such cases, a forensic anthropologist may be called in to judge the times of death so the order in which victims were killed can be determined.
The world's most prolific serial killer was Dr. Harold Shipman, a British physician who took his own life in prison in 2004. He may have been responsible for up to 300 deaths, but the true figure will never be known as he always denied the killings. Prior to this, the so-called "Monster of the Andes," Pedro Lopez, held this dubious distinction, having been convicted of 57 murders in 1980. He may have killed many more; his victims were young girls in Colombia.
Despite his notoriety, Shipman was, in many ways, an unusual type of serial killer. His victims, many of whom were elderly women, met their end through morphine injections, one of the main methods of assisted suicide, which some believe to be a compassionate act. He was well known and liked in his community, and there was no obvious motive for the crimes. Some psychiatrists have suggested Shipman disliked older women, or that he was trying to re-enact the death of his mother. Others believed he gained pleasure from the power of life and death that he could exercise as a doctor. Shipman may have begun to kill patients very early on in his medical career, before he had even finished training to be a doctor. Initially, it was thought he began his career as a serial killer in 1974 when he first became a family doctor. This would put the number of deaths between 216 and 260. If, however, he began to kill almost as soon as he had the opportunity, then at least 24 more deaths, and maybe more, could have been at the hands of Shipman.
SEE ALSO Bundy (serial murderer) case; Psychological profile; Psychopathic personality.