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Finding a Serial Killer—and Justice—After 40 Years

Last winter, police in Denver, Colorado, announced that they had solved the cold-case murders of four women who had died about 40 years ago, all of whom had been the victims of one man—a previously unknown serial killer named Joe Michael Ervin.

 The story was chillingly real but sounded like a crime novel. In the late 1970s and early 1980s, Ervin took the lives of four women who appeared to have nothing in common. They did not know each other and differed in age, race, and appearance. At the time, the cases did not appear to be related, and Ervin was never a suspect in any of them. Shortly after the fourth murder, Ervin shot and killed a police officer during a traffic stop. He later took his own life while in jail.

How, after so many years, was the truth uncovered? It took years of old-school police work and a cutting-edge investigative technique called forensic genetic genealogy (FGG). It took the combined efforts of law enforcement in Colorado and Texas, along with support from the Bureau of Justice Assistance (BJA), which used two different grants to help crack the case.

And it took the efforts of two determined investigators—Detective Kari Johnson of the Denver, Colorado. Police Department and Dr. Angela Williamson, the Forensics Unit Supervisor at BJA–who recently shared this remarkable story on the Justice Today podcast.

Dr. Williamson and Detective Johnson became involved in the Joe Michael Ervin case about four years ago. Detective Johnson inherited an open investigation when she joined Denver’s cold-case squad in 2018. DNA evidence had linked the four murders to a single perpetrator, but years of police work had eliminated all known suspects.

That was when Detective Johnson’s team began using FGG, on which Dr. Williamson is an internationally recognized authority.

"For quite some time now, genealogists have been using publicly available ancestry databases," Dr. Williamson told Justice Today. "You can submit your own DNA sample, which is usually just saliva from your mouth on a swab. And based on the DNA, then you can trace your ancestry.

"Using that same methodology, you can upload a DNA profile from an unknown person—in this case, an unknown murderer,” Dr. Williamson said. “Then you can mine these databases to see if you can find any relatives. Typically, it’s not the person who’s responsible for the crime. It’s usually not even a close relative, like a sibling. It’s often a very distant relative, like a third cousin twice removed. And then that’s where the hard work comes in."

Detective Johnson’s team in the Denver cold-case unit spent months using FGG to construct family lines that traced the perpetrator’s family to Texas. She requested assistance from the Texas Rangers, and in June 2021, several Rangers asked her to join them on a conference call.

"Through all of this, there are so many emotional highs and lows, because you think we’re on the right track, and then you get big goose eggs,” Detective Johnson said. “But there were 11 participants on that call. So, we figured it was good news."

The Rangers had found a potential familial DNA match to a Texas offender named Paul Ervin. Detective Johnson already knew that Paul Ervin was not their killer because his DNA was not an exact match to samples from the Denver-area crime scene. “But his jail intake paperwork listed a brother that we had not heard of,” Detective Johnson said. “And that brother was Joe Michael Ervin.

"We are still on that call when my phone starts dinging," she said. "And it's Tracy Carlson from the lab, and she's, like, 'I just found a marriage certificate in Colorado for Joe Ervin . . . I just found a residential address for Joe Ervin in Denver around the time of our murders,' . . . So, through all of this, we’re, like, this has to be our guy."

Investigators discovered that Joe Michael Ervin had been buried in a family plot in Texas. To confirm he was the killer, they would need to exhume his body. Exhumations are complex and expensive, and the BJA grant that supported the Denver cold-case investigation did not pay for exhumations. But Dr. Williamson had an idea.

"There was a grant that got Kari through 90 percent of the investigation, nearly all the way to the end," Dr. Williamson said. "But they were not able to use that grant to finally resolve this case. A simple answer would have been, 'Sorry, you can't use grant money for it, try and find it somewhere else.' But that's not how we function."

Dr. Williamson knew that BJA had also awarded the Texas Rangers a separate grant under the Sexual Assault Kit Initiative (SAKI) program. “It was just a natural solution to see if we could utilize the SAKI grant that the Texas Rangers had to help out in this case,” she said. “Not only did the grant permit activities like exhumations, but their grant also focused on violent serial offenders in Texas. That’s why, for the first time ever, we leveraged two grant programs to get one answer for all these families and a sense of justice for the victims.”

Not long after Ervin’s body was exhumed, DNA evidence definitively proved that he had killed all four of the Denver-area victims. And Detective Johnson was able to contact the victims’ families to tell them these cases had been solved.

"A lot of people have asked, 'What does this feel like?'" Detective Johnson said. "And there's such a variety of responses I could give, and emotions that come attached to them. The biggest one is telling these families who have waited 40 years, who had given up hope and had thought they would never find answers about what happened to their loved ones. Having those personal conversations with them, it’s life changing in so many ways.

"But there are so many important cases,” Detective Johnson said. “Utilizing these grants that Angela and BJA awarded us, my partner in the cold-case unit just made an arrest on a kidnapping sexual assault. So, I’m excited about being a part of this generation of investigator where these things are available to us."

To learn more about this story, listen to the Justice Today podcast.