A new study from the Federal Bureau of Investigation sheds light on the mysterious world of serial murderers in hopes of helping investigators solve the rare and baffling crimes.
Serial Murder: Pathways for Investigations, the work of retired FBI veteran Robert Morton, crime analyst Jennifer Tillman and research analyst Stephanie Gaines, is an investigation of 480 serial murder cases involving 92 killers over 46 years in the United States. The researchers spent five years studying the crimes and attempting to establish a new methodology for identifying serial killers that is based on how and where the victims’ bodies are discovered.
“You work your way back from there to discern offender characteristics and narrow the suspect pool, ”Morton said in an FBI news release. “The body is the only constant in the crime. Lots of other things can change, but how you find that victim is not going to change.”
According to the study, several factors can make it particularly difficult to solve serial killings. First, most criminal investigators have little experience dealing with serial murders because they don’t happen often. In addition, many serial killers are sexually motivated and often operate in ways that can be difficult for the inexperienced to understand. Myths propagated by the media and in the entertainment industry – for example, that all serial killers are white men – can also be difficult to overcome during an investigation.
Past studies of serial murderers have focused mostly on the backgrounds of known offenders. This line of inquiry has emphasized a killer’s upbringing, familial relationships, histories of emotional, physical or sexual abuse and other factors. Much of the information in these studies was gleaned from interviews with the killers themselves.
“The majority of previous research on serial murder has given minimal assistance to law enforcement working unsolved serial murder cases,” Morton and his colleagues wrote.
The FBI’s National Center for the Analysis of Violent Crime undertook the new study to fill the research gap and, more importantly, to help investigators dealing with ongoing cases. The researchers focused on how and where the killers disposed of their victims’ bodies to determine the approach a killer used to gain access to a victim, the motivation for the killings and the nature of the victim-offender relationship.
The researchers separated the “body disposal scenarios” into four categories or pathways: transported from murder site and concealed; transported from murder site and dumped; left “as is” at the murder site; and left at the murder site and concealed. These scenarios can help give investigators important clues about the perpetrator. For example, different methods of body disposal can be indicative of various levels of criminal experience. The way in which a killer chooses to dispose of a victim’s body can also shed light on the nature of the crime.
The study found that killers used a ruse or a con to gain access to their victims in about 65% of the cases studied. They used surprise in nearly 17% of the cases, a blitz in 5% and an unknown tactic in the remaining 12.5%. The most common relationship between killers and their victims (41.5%) was client or customer. In more than 30% of cases, the parties were strangers, while in 12% of serial murders they were acquaintances. The victims were “targeted strangers” in almost 12% of the cases.
Studying the character of the crime scene can help investigators effectively link crimes to a single killer by identifying commonalities across slayings. Cases can be linked in a number of ways, including the causes of death, characteristics of the victims, the use of a similar weapon across multiple killings and geographic locations.
“The main goal is to provide law enforcement with relevant data that helps them focus on the most likely suspects,” Morton said in a statement.