There has always been a fascination with serial killers. From Jack the Ripper to John Wayne Gacy, these figures have both terrorized and captivated people. As it turns out, some of these well-known offenders exhibited a similar trait early on before their crimes escalated.

Scott Bonn, Ph.D., recently told Oxygen that several of the most notorious murderers began experimenting with pushing the boundaries in their teen or early adult years. This came in the form of starting out as peeping toms. 

"It's a violation of privacy and it does lend itself to power and control," Bonn stated, adding, " [Ted] Bundy and BTK [Dennis Rader] were all about power and domination and control."

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According to the criminologist, voyeurism or peeping on others can be a step in their natural evolution of criminal activity, as he states no one wakes up and suddenly decides to become a serial killer. "It doesn't work that way," he explained.

Paul Holes, a retired investigator for the Contra Costa County District Attorney's Office, added onto that sentiment by saying that in order for someone to evolve into a serial killer they must overcome a series of "barriers." Furthering his point, Holes, who played a pivotal role in capturing suspected Golden State Killer Joseph DeAngelo, stated that the typical person would feel uncomfortable walking into their neighbor's yard and spying into their windows without permission.

According to Holes, future serial killers also share that same feeling of unease, which is why they have to work to overcome the hesitation. Due to this, they start off by committing acts that "have less significant societal barriers," reported the outlet. Eventually, Holes said that this behavior will escalate and manifest in ways, such as entering homes when its residents leave or stealing certain belongings. 

An example of this behavioral pattern could be seen in DeAngelo, who was arrested in 2018 for 13 murders associated with the Golden State Killer, as he too started off secreting watching people. Then, he began burglarizing homes between 1974 and 1975 and peeping in windows. "If they continue to evolve, they are the ones who are ultimately going to want to get into somebody's house and ultimately sexually assault or kill," Holes stated.

Bonn also recently spoke with Dennis Rader, known as the BTK Killer, who admitted that he had watched women before committing murders in Wichita, Kansas. Although this pattern is troubling, fortunately, not all peeping toms turn into murderers.

"Certainly, a very, very, very small subset of all peeping toms are serial killers but I would say becoming a peeping tom or being a peeping tom is a very logical and natural stage in the progression of a fledging future serial killer," Bonn concluded.