Experts are still attempting to understand the minds of serial killers. Patrick Harbron/Netflix

The following is an adapted excerpt from "The Big Book of Serial Killers: 150 Serial Killer Files of the World's Worst Murderers" by Jack Rosewood:

While there is still no simple thread of similarities – which is why police and the FBI have more trouble in real life solving crimes than they do on shows like "Criminal Minds"– there are some things to look for, experts say.

Antisocial Behavior

Jeffrey Dahmer didn't try to make any friends. AP

Psychopaths tend to be loners, so if a child who was once gregarious and outgoing becomes shy and antisocial, this could be an issue. Jeffrey Dahmer was a social, lively child until his parents moved to Ohio for his father’s new job. There, he regressed – allegedly after being sexually molested – and began focusing his attention on dissecting road kill rather than developing friendships.

Arson

Fire is power, and power and control are part of the appeal for serial killers, who enjoy having their victims at their mercy. David Berkowitz was a pyromaniac as a child – his classmates called him Pyro as a nickname, so well-known was he for his fire obsession - and he reportedly started more than 1,000 fires in New York before he became the Son of Sam killer.

Torturing animals

The Boston Strangler would capture cats and dogs as a child and torture them. Getty Images / Stringer

Serial killers often start young, and test boundaries with animals including family or neighborhood pets. According to studies, 70 percent of violent offenders have episodes of animal abuse in their childhood histories, compared to just 6 percent of nonviolent offenders. Albert DeSalvo – better known as the Boston Strangler – would capture cats and dogs as a child and trap them in boxes, shooting arrows at the defenseless animals for sport.

A troubled family history

Many serial killers come from families with criminal or psychiatric histories or alcoholism. Edmund Kemper killed his grandparents to see what it would be like, and later – after he murdered a string of college students – he killed his alcoholic mother, grinding her vocal chords in the garbage disposal in an attempt to erase the sound of her voice.

Childhood abuse

Aileen Wuornos, a rare female serial killer, was physically and sexually abused. Getty Images / Handout

William Bonin – who killed at least 21 boys and young men in violent rapes and murders – was abandoned as a child, sent to live in a group home where he himself was sexually assaulted. The connections suggest either a rage that can’t be erased – Aileen Wuornos, a rare female serial killer, was physically and sexually abused throughout her childhood, resulting in distrust of others and a pent-up rage that exploded during a later rape - or a disassociation of sorts, refusing to connect on a human level with others for fear of being rejected yet again.

Substance abuse

Many serial killers use drugs or alcohol. Jeffrey Dahmer was discharged from the Army due to a drinking problem he developed in high school, and he used alcohol to lure his victims to his apartment, where he killed them in a fruitless effort to create a zombie-like sex slave who would never leave him.

Voyeurism

Ted Bundy used to peep through girl's windows. AP

When Ted Bundy was a teen, he spent his nights as a Peeping Tom, hoping to get a glimpse of one of the neighborhood girls getting undressed in their bedrooms.