"He was scary smart": Laura Greenberg delves into twisted experiences with serial killer Douglas Gretzler as Oxygen drops Charmed by the Devil

In the autumn of 1973, a spate of violent crimes broke out in Arizona and California. Douglas Gretzler, who was 22 years old at the time, and his accomplice Willie Steelman, 28, went on a three-week murdering spree that claimed the lives of 17 people.

Their initial plan for a drug party road trip quickly escalated into a series of robberies, kidnappings and killings. Their targets ranged from hitchhiking strangers to families. Their crime spree finally came to an end with the murder of nine members of two families in Lodi, California, on November 6, 1973.

The police finally picked them up in Sacramento a few days later, thanks to a tip from a hotel clerk. Both Douglas Gretzler and Steelman pleaded guilty to their crimes but could not explain their motivations. That is, until journalist Laura Greenberg came onto the scene in the 1980s.

She was corresponding with Gretzler from Arizona's death row, where he resided for over 40 years, exchanging thousands of letters and recording more than 500 conversations with him. Their new documentary, "Charmed by the Devil," aired on Oxygen TV on December 13, 2025.

This special is a three-part series with never-before-heard audio recordings, delving into the emotional side of what it means to be a profiler. This is a little-known piece of American crime history.

Charmed by the Devil: The 1973 killing spree of Douglas Gretzler and Steelman

The murders began on October 18, 1973, in Colorado. Douglas Gretzler and Steelman kidnapped two men, Ken Unrein and Mike Adshade, during a robbery attempt. They bound the victims and strangled them with a belt in a remote ravine.

Moving to California, the duo stole a car from a couple, with Steelman assaulting the woman, but they let the pair go alive. By October 22, back in Arizona, they shot hitchhiker Steve Loughran in the head. Days later, they killed Bob Robbins, a gas station attendant, and Yahfah Mestistes, a student they robbed, as per Oxygen.

On November 1, the killers chased hitchhiker Gilbert Sierra into a desert embankment and shot him. Two days later, in Tucson, they forced their way into the home of Marine Captain Michael Sandberg and his wife, Patricia. Steelman shot Patricia, and Douglas Gretzler killed Michael to cover their tracks.

The violence peaked on November 6 in Lodi, California. After a failed store robbery, they invaded the Parkin family home, taking nine hostages: Debbie Earl, Ricky Earl, Lisa Parkin, Robert Parkin, Richard Earl, Wanda Earl, Mark Lang, Wally Parkin and Joanne Parkin. 

The men tied up the victims, shot the children first, then executed the adults one by one. Police caught them that evening in Sacramento. The spree covered over 1,000 miles and shocked communities on both sides of the border, according to Oxygen.

Laura Greenberg's quest for answers

Laura Greenberg first learned of Gretzler's case in the early 1980s through news reports. As an investigative journalist, she decided to contact him on death row in Arizona. Her goal was straightforward: to explore why a seemingly ordinary young man committed such acts.

Starting with letters, she built trust over time. Gretzler, executed in 1998, responded openly, sharing details of his troubled youth and the road trip that spiralled out of control, as per the Independent. Greenberg visited him in prison multiple times, recording conversations that lasted hours.

She collected over 500 hours of audio, where Douglas Gretzler confessed to the murders in graphic detail, including the Lodi massacre. He described the pact he made with Steelman to kill if needed during crimes, but claimed no deeper plan.

Greenberg also gathered letters, hundreds exchanged over decades, covering not just the killings but his daily prison life. Her work uncovered new insights, like Gretzler's reading of In Cold Blood before the spree, which police found in his possession, according to Oxygen. 

Though Steelman died in 1986 from liver failure, Greenberg focused on Gretzler's perspective. The tapes, kept private until now, reveal his calm demeanour when recounting the deaths. Her persistence filled gaps left by official records, providing a voice to the unanswered questions.

The blurring lines: An unexpected bond

As years passed, Greenberg's project evolved beyond journalism. What began as fact-finding turned personal. Douglas Gretzler shared intimate thoughts, ranging from family regrets to philosophical ideas, leading to discussions about a wide range of topics. 

Boundaries faded; she admitted thinking of him constantly. In a striking gesture, he sent her a lock of his hair, which she kept as a memento, according to Oxygen. Experts in Charmed by the Devil note how such interactions can create emotional ties, even with killers.

Greenberg reflected on the risk, saying she "wanted to understand the monster" but got drawn in. The documentary includes clips from her recordings, showcasing Gretzler's "scary smart" side, which is articulate and manipulative. He discussed his intelligence as a tool in committing crimes, planning escapes and creating alibis.

“We were both obsessed with the human mind,” Greenberg said in a clip shared with The Independent.

When asked how a connection was formed, she said:

“He was scary smart. I had to really use my brain.”

After his execution, Greenberg continued analysing the tapes, grappling with the toll. The film highlights her isolation and second-guessing, as colleagues questioned her methods. Yet it also credits her for preserving rare insights into a killer's mind. Families of victims, though pained by revisiting the case, appreciate the motive exploration.

Catch Charmed by the Devil streaming on Oxygen.