David Carpenter: The Serial Killer Who Made California Parks His Human Hunting Ground

It was the autumn of 1980, and the majestic forests and dramatic headlands just north of San Francisco were devoid of tourists. A brutal murderer was on the loose: the "Trailside Killer," so-dubbed by local press because he targeted young women for rape and murder on sparsely populated wilderness paths in the beautiful parks system around the Bay Area, driving the public into a panic.

Over a six-week window, the killer murdered at least five people: Anne Alderson, 26, in Mount Tamalpais State Park; and Diane O'Connell, 22, Shauna May, 25, Cindy Moreland, 18, and Moreland's fiancé Rick Stowers, 19, who were all found on the same day in shallow graves at Point Reyes National Seashore.

How Law Enforcement Cracked the Case

Ballistics confirmed law enforcement's fears: All the murders were committed using the same .38-caliber pistol, so police knew early on that they had a serial killer on their hands. But seeing the connection didn't give them any suspects. Their big break didn't come until March 27, 1981. That's when the killer attacked Ellen Hansen and her boyfriend Steven Haertle, University of California-Davis students who were camping and hiking at Henry Cowell Redwoods State Park. Hansen was shot multiple times in the head and killed; Haertle was shot in the chest but managed to escape. He later gave investigators a description of the assailant: 45 to 50 years old, with dark hair and hazel eyes. It was the first survivor they had.

Just over a month later, in May, 20-year-old Heather Scaggs disappeared after telling her boyfriend and her mother that she was going to see a co-worker, David Carpenter, 50, about buying a used car from him. Carpenter had a lengthy rap sheet of rape and assault, and when investigators went to question him, they noticed he matched the description Haertle had provided them. His car also matched one seen by eyewitnesses at several of the murder scenes. They made their arrest soon thereafter. Scaggs's body was found in Big Basin Redwoods State Park later that month.

John Posey, who was the senior deputy district attorney for Marin County at the time and prosecuted five of Carpenter's murders, credits multiple people for Carpenter's arrest, including the San Jose police officers who first interviewed the killer as well as Haertle.

"In my opinion, he's the best eyewitness I ever had," Posey tells A&E Crime + Investigation. "Carpenter had crooked teeth. I watched film clips with him and I wasn't picking up that he had crooked teeth. And Haertle picked that up. The composite they did based on his description was remarkably close."

The Trailside Killer's Early Roots

Carpenter grew up in San Francisco. He suffered from a severe stutter, and was institutionalized as a teenager for molesting his younger cousins. According to Posey, his early experimentation with sexual violence was indicative of a sociopathic personality disorder.

"A lot of these personalities start at a very, very young age," says Posey. "And that kind of personality really doesn't stop committing crimes."

Carpenter hadn't. He'd assaulted a young woman, Lois DeAndrade, with a hammer and a knife in 1960, for which he was convicted and served 7½ years. Within nine months of his release he began assaulting women again, and in 1970 he was convicted of robbery, kidnapping and rape.

In May 1979 he was paroled. Because Carpenter was a serial killer and never confessed to any crimes it's impossible to say when he first killed after being release. But his DNA was later identified at the murder scene of Mary Frances Bennett, a 23-year-old whose body was found in San Francisco’s Golden Gate National Recreation Area in October of that year.

After he was convicted, Carpenter's attorney argued that his client deserved to be spared the death penalty because of the difficulties of his childhood, telling reporters at the time that his client was a "mental mess" and a "personally damaged human being" who'd suffered at the hands of abusive parents.

Says Posey: "I remember some evidence being presented [by the defense]: that he had to wear shorts at school. And that was a bad thing."

Posey didn't buy it.

Carpenter on the Witness Stand

According to Posey, Carpenter was a masterful manipulator.

"Depending on who his audience was, that was the version of himself that he'd tell," Posey said, noting that early in Carpenter's criminal career, court psychiatrists would write him favorable mental-health evaluations, or that several of the women he assaulted were convinced against their better judgement to go to secluded places with him.

For seven days Carpenter sat on the witness stand in his case with Posey, during which time he seemed to show tremendous emotional volatility.

"Sometimes he'd be jovial. Sometimes he'd be serious. Sometimes he'd be sad about something," Posey says.

As to whether or not this was a killer devoid of emotions, Posey said it didn't seem that way by outward appearances.

"There was a time or two where he shed some tears," says Posey. "He showed empathy."

Any humanity Carpenter showed on the stand was overshadowed, however, by the gruesomeness of his deeds.

"It's just horrendous," Posey says. "The last day of the trial, I had one of the lead investigators come in and summarize the crime scenes. And I've never been in a courtroom where you could feel what the jury was feeling like that. You could've dropped a pin in that courtroom."

Carpenter was sentenced to death for his crimes. He's currently housed on death row at San Quentin State Prison and, at 89 years old, is the oldest death row inmate in California.

Posey doesn't regret pursuing the death penalty, and says Carpenter deserves to be put to death for his crimes.

"If they're going to have the death penalty," Posey says. "It's for this kind of case."