Speculation about who might be the alleged serial killer dumping human remains along beaches on Long Island may be unwarranted so early in the investigation, criminologists say. But despite having diverse motives, serial killers do tend to share certain personality traits, and experts are learning more about what makes these killers tick, including a desire to convince others that they're "good people."
News outlets have reported that police are considering the possibility that some of the killings were committed by a police officer or ex-police officer. One psychic is even claiming credit for predicting (very vaguely) where one of the bodies would be found. But at this stage in the investigation, criminal psychologists and criminologists say, it's too early to jump to conclusions regarding the perpetrator.
"Unless you are directly involved in the case, you've been at the crime scene, you've seen all the files, anyone else is just using the typical white male, mid-to-late 20s profile," said Michael Aamodt, a professor of psychology at Radford University in Virginia who maintains a research database of more than 1,700 convicted serial killers.
When you break down the numbers, Aamodt told LiveScience, that profile accounts for less than one in five serial killers. In research presented in 2007 at a Society for Police and Criminal Psychology meeting in Massachusetts, Aamodt and his co-authors found that of the killers in their database, 90 percent were male and 74 percent were white. But when all of the demographic variables were combined, only about 18 percent of killers were white males in their mid-to-late 20s.
Motives for murder
The problem with profiling the average serial killer is that there is no such thing, said Stanton Samenow, a criminal psychologist and author of the book "Inside the Criminal Mind" (Crown, 1984). [Read: Criminal Minds Are Different From Yours]
Serial killers — the term that generally refers to someone who kills three or more people with a "cooling off" period in between murders, though some experts argue that the definition should include killers with two victims — have many motivations, Samenow told LiveScience. Some kill for money, others for revenge and still others for the thrill of it.
In many ways, serial killers are similar to other chronic criminals, Samenow said.
"These are people for whom life is not acceptable unless they have the upper hand," he said. "They have a view of themselves as being the hub of the wheel around which everything else should revolve."
The development of a serial killer is not well-understood, Samenow said, including the role of childhood abuse.
"You can ask eight experts and get 10 opinions on that," he said. His take, he said, is that serial killers come from all walks of life. They often show early personality traits such as a need to be in control and the refusal to take responsibility for wrongdoing, but the factors that create these traits aren't known.
While convicted serial killers often report childhood abuse, Aamodt said, he warned that the refusal to take responsibility for their actions means that serial killers' childhood reminiscences should be taken with a grain of salt.
"It's probably not surprising that serial killers would lie," Aamodt said.
Samenow, who has interviewed multiple serial killers, said the Ted Bundy-style stereotype of a personable — even charismatic — serial killer is often true.
"Sometimes it's even hard to remember while you're talking to them, that they've done the terrible things that they've done, because they can be very winsome and charming," Samenow said.
One thing almost all of the serial killers he's interviewed have in common is a desire to convince him that they're good people at heart, touting their musical or artistic talents or all the good things they've done in life, Samenow said.
"I remember one guy who said, 'Well, just because I killed somebody doesn't make me a bad person,'" Samenow said.
Police have identified four of the bodies found on Long Island as young women, all of whom were working as prostitutes when they disappeared. The remains of five or six more people have recently been found, but those bodies have yet to be identified. Police aren't yet sure whether the victims are from one killer or several, though they have linked the killings of the four identified women.
"It's a very difficult investigation," said Steven Egger, a serial killer expert and criminologist at the University of Houston, Clear Lake. "It's going to take time."
Egger said the main similarity among serial killers is their choice in victims.
"The victims are vulnerable. That's the key," Egger told LiveScience." I don't care if the killer's psychotic or psychopathic or out for money, they're still going after vulnerable victims."
That makes the Long Island killer or killers' choice of prostitutes very typical, Egger said. Prostitutes are what he calls the "less-dead," people who fall through the cracks of society and are less likely to be looked for or linked together.
Even when a serial killer case becomes famous, Egger said, the victims remain overlooked.
"The highlight, the interest in serial killers is about the killer, it always has been," Egger said. "We come up with names for them, like 'The Hillside Strangler' or 'The Night Stalker' … People forget about the victims."
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Stephanie Pappas is a contributing writer for Live Science, covering topics ranging from geoscience to archaeology to the human brain and behavior. She was previously a senior writer for Live Science but is now a freelancer based in Denver, Colorado, and regularly contributes to Scientific American and The Monitor, the monthly magazine of the American Psychological Association. Stephanie received a bachelor's degree in psychology from the University of South Carolina and a graduate certificate in science communication from the University of California, Santa Cruz.