In February 1993, Salt Lake City hosted the NBA All-Star Game. That same weekend, 35-year-old Theresa Morlock was strangled inside her apartment on South Redwood Road. A friend had met the man she was with hours earlier — from Arizona, in town for the game — but never got his name. Her body was found two days later by a maintenance man who had come to repossess a microwave.
Investigators recovered an unknown DNA profile from her body in 1993 and entered it into CODIS, the national DNA database, where it sat without a match for three decades — because CODIS can only find a match if the person’s profile is already in the system. An early suspect was charged based on other evidence, then cleared by that same DNA testing; the charges were dropped.
What finally broke the case was a single hair, recovered beside one of the bite marks in 1993 and preserved in evidence ever since. In 2026 it was sent to Intermountain Forensics, a nonprofit forensic genetic genealogy laboratory in Salt Lake City. The DNA produced a match at roughly third-cousin level. Investigators built a family tree outward from that match, and one branch led to a man who had once lived in Arizona: James Wallace Petersen III.
Petersen, now 63 and living in Cedar City, Utah, pleaded guilty to murder on July 27, 2026. On September 21, 2026, Judge Kristine Johnson sentenced him to five years to life — the sentence Utah law prescribed for first-degree murder back in 1993, the year of the crime. The legislature has since raised that range to fifteen years to life. In practice the gap is narrower than it looks: Adult Probation and Parole recommended roughly 20 years before parole eligibility, which at age 63 is likely to amount to the rest of his life.
The full story — the investigation, the cleared suspect, how forensic genetic genealogy actually works, and the arrest — is in the video below.
Related reading
No well-reviewed book has been written about this case specifically. For readers who want more on the forensic genetic genealogy that solved it: search results on Amazon.
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Sources
Salt Lake County District Attorney’s Office press releases (March 12, July 28 and September 21, 2026); Salt Lake City Police Department news release, March 12, 2026; reporting by KSL.com, Gephardt Daily, FOX 13 News Utah (KSTU), KUTV and ABC4; Third District Court charging and sentencing proceedings; Deseret News death notice for Theresa Ann Morlock, February 28, 1993. Full slide-by-slide image credits appear in the video description. No identification photograph of the victim or the defendant was publicly released in this case, so none appears in this video.
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