by San Francisco — After more than four decades, authorities have secured a conviction in one of the city’s oldest unsolved homicides. An 80-year-old Colorado man has been found guilty of the 1978 murder of a teenage girl from New York, bringing long-awaited justice to a family that has waited nearly 47 years for answers.
Teen’s Trip to San Francisco Ends in Tragedy
Officials announced Thursday that Mark Stanley Personette, of Jefferson County, Colorado, was convicted of first-degree murder in the killing of 15-year-old Marissa Rolf Harvey.
Harvey had been visiting San Francisco from Queens, New York, during Easter break in March 1978. On March 27, 1978, she headed to Golden Gate Park for an afternoon of horseback riding. She never returned to her sister’s home.
The next morning, surfers walking through nearby Sutro Heights Park discovered her body. Authorities said she had been sexually assaulted and strangled, setting off a massive investigation that, despite early progress, eventually went cold.
District Attorney Brooke Jenkins praised the verdict, stating:
“At long last, justice has been delivered, and Mr. Personette is being held accountable for this horrific crime… Although nothing we do can bring the victim back, I pray this verdict gives the family a sense of closure.”
Early DNA Testing Provided Clues but Not Answers
Investigators made a breakthrough in the early 2000s when primitive DNA analysis detected a male DNA profile on Harvey’s sweater, jeans, and even on a piece of dried chewing gum stuck to her clothing.
Despite these discoveries, law enforcement lacked the technology and national database capabilities to identify a suspect. Detectives tracked down every lead they could, but without a match, the case stalled for years.
Read Also: Police: Man Posted Photo with Ex on Facebook After Allegedly Stabbing Her to Death
Cold Case Reopened With New Forensic Tools
In October 2020, San Francisco’s homicide cold-case unit took another look at the evidence using advanced DNA testing techniques unavailable in earlier decades.
By 2021, investigators used investigative genetic genealogy to pinpoint Personette as a potential suspect. They placed him under surveillance, gathering discarded items to compare his DNA to evidence from the crime scene.
According to prosecutors, FBI agents observed Personette disposing of trash in a Walmart parking lot more than 15 miles from his home. The trash contained only personal hygiene items, which investigators say appeared intentionally separated—behavior that raised significant suspicion.
When police searched his residence, they discovered additional items linking him to the Bay Area in 1978, including 1970s-era maps of San Francisco and a set of California license plates with a 1979 registration sticker. This directly contradicted Personette’s claim that he had never been in San Francisco.
Subsequent DNA tests confirmed that Personette’s DNA matched the samples found on Harvey’s clothing and the dried gum.
Prior Assault Testimony Strengthened the Case
During the trial, prosecutors introduced testimony from another woman who said Personette raped her in 1979, one year after Harvey’s murder, when she was 16 years old in a wooded area of New Jersey. The court allowed the testimony under rules permitting evidence of prior sexual offenses to establish patterns of behavior in violent crimes.
Assistant District Attorney Heather Trevisan emphasized the extraordinary collaboration and perseverance behind the case:
“This case shows that time cannot thwart justice… I have not seen, in 25 years, more people willing to sacrifice their time and personal comfort to do their duty.”
Sentencing Set for December
Personette now faces a sentence of seven years to life in prison, reflecting California’s sentencing laws at the time of the crime. His sentencing hearing is scheduled for December 17.
For Harvey’s family, the verdict marks the end of a decades-long wait for accountability — a reminder that even after nearly half a century, cold cases can be solved through determination, science, and persistence.
Stay Updated
For continued coverage of major crime developments, justice updates, and national news, visit mikeandjonpodcast.com.
