Why Did 'BTK Killer' Dennis Rader Keep Photographic Evidence of His Crimes?

Warning: The following contains disturbing descriptions of violence, including sexual violence. Reader discretion is advised.

Over the course of nearly two decades, Dennis Rader murdered at least 10 people in the Wichita, Kan., metropolitan area. Despite his repeated taunts to police and the media under the pseudonym BTK ("Bind, Torture, Kill"), investigators were unable to hone in on a suspect. No one imagined it was Rader—not his colleagues, nor his family, nor the police force he was mocking.

Rader's successful evasion was a testament to the care he took to avoid detection. He'd cultivated a good name for himself as a Boy Scout leader and a church congregation president, roles which also afforded him false alibis. He spent weeks premeditating his kills—mapping out his victims' homes, then cutting phone and alarm systems before entering the house, skills he had learned while working a past job for ADT Security.

But for all his dodges, Rader was captured with a treasure trove of irrefutable self-incrimination: numerous Polaroid photographs of his victims and crime scenes, alongside countless confessional notes. Some of the photographs he'd taken long after the murder, meaning that in addition to the risk of owning the photos, he'd also taken the subsequent risk of visiting a buried victim to take more pictures of their decomposing corpse. And rather than lock up the photos in a single secure location, Rader stored them in multiple places: at home, at his workplace and at his church.

Rader is hardly alone in preserving criminal evidence, despite the obvious problems inherent to doing so. Park Dietz, a clinical professor of psychiatry and biobehavioral sciences at the University of California, Los Angeles, estimates that "50 to 75 %" of serial sexual offenders keep evidence of their crimes.

Dietz tells A&E Crime + Investigation it's overly simplistic to view these photographs as a "tool to facilitate subsequent arousal."

"They are used for that, but that's only part of the story," Dietz explains. "The behavior is best understood as the offender's desire to capture the victim, and his conquest of the victim, forever. The central issue is possession: how to possess the victim and her fear, her response [and] her suffering, [as well as] his power, his conquest and his pleasure."

The desire for control was central to Rader's psychopathology. In addition to the more obvious manifestations of his control impulse—he tied his victims up and controlled their access to oxygen via protracted, torturous strangulations—Rader also fantasized about controlling his victims in the afterlife. In Rader's idea of heaven, each victim continued to serve him as a slave.

Nola Foulston, the former district attorney of Sedgwick County, Kansas, who prosecuted Rader, says that the documentation he created of his crimes was extensive—and went far beyond a few snapshots immediately after a kill.

"He collected bras. He collected underwear. He took pictures of himself in the clothing of the women. He would do all kinds of weird s---," Foulston tells A&E Crime + Investigation.

According to testimony by Sgt. Tom Lee, a sheriff's investigator, in one of the more disturbing photography sessions, Rader sexually assaulted and killed his 53-year-old neighbor, Marine Hedge; then he took her corpse to his church, where he posed her dead body for a series of photographs.

The behavior aligns with Dietz's theory of Rader's control impulse.

"If a sexual serial killer could have an entire prison with his victims captured and a catacomb of his victims who died, he'd be very happy," Dietz says. "But that requires owning a lot of real estate and going through a lot of work. This is a substitute."

Rader's extensive documentation also applied to victims he hadn't gotten around to killing yet. Rader admitted to having several incomplete "projects" (his word for his premeditated murders). Foulston says investigators found "little white cards" at Rader's home, scribbled over in notes, some of which had photographs attached.

"On a daily basis, this guy was pulling out his cards," Foulston says. "He probably had 400 cards. And one of them was me. He had written my name on the back of a card."

The collecting of victim paraphernalia wasn't limited to Rader's human victims, either. Rader served as a dog catcher in Park City—a suburb of Wichita—and Foulston says that when Rader was arrested, Wichita police also found an assortment of dog collars.

"He had a very active, very twisted life," Foulston says.

Where Rader diverges from many serial killers is that his fantasy seemed to also include his own victimhood. In many photographs, Rader would dress himself up as his victims: wearing their clothing, burying himself in a shallow grave or binding himself up in a tree.

"When I interview offenders and ask if they've ever thought about being victims, the usual response is 'Are you crazy, doc?'," says Dietz. "But Rader, I think, must've been both [sadistic and masochistic]. It was erotic for him to be bound, to be cross-dressed, and to strangle himself."

Contrary to popular belief, lots of uncaught serial killers "retire" from their crimes as they grow old, and Rader could've easily gotten away with his crimes and died undiscovered. His final confirmed murder was in 1991, and he wasn't arrested until 2005—shortly after he renewed correspondence with police and media following a decade of silence.

Rader sent a computer floppy disk to police, which they were able to digitally trace back to his church. Subsequent DNA testing on Rader's daughter gave police the information they needed, and Rader was detained. On interrogation, he admitted to his crimes.

"He would've never been caught if he hadn't acted like a perfect idiot," Foulston says.