More than four decades after a teenage girl was brutally killed, an 80-year-old man has been sentenced to life in prison for the 1978 murder.
Mark Stanley Personette received the sentence on Wednesday for the killing of 15-year-old Marissa Harvey, whose case remained unsolved for nearly 50 years.
Harvey, a New York resident, had been visiting her older sister in San Francisco. She disappeared after setting out on a day trip to Golden Gate Park, where she planned to go horseback riding.
Surfers discovered her body the following day at nearby Sutro Heights Park. Prosecutors said she had been sexually assaulted, severely beaten and strangled with a ligature.
Personette was finally arrested in Denver, Colorado, in December 2021—43 years after the teenager’s death.
Following the arrest, the San Francisco Police Department said investigators had pursued every available lead during the original inquiry and used the most advanced technology of the era. Despite those efforts, the case eventually went cold.
The investigation was reopened in 2021 after advanced DNA analysis and investigative genealogy identified Personette as a suspect, prosecutors said.
DNA testing conducted in the early 2000s had detected a male profile on Harvey’s sweater and jeans, along with a piece of dried chewing gum found stuck to her back. At the time, however, investigators could not connect the profile to a specific person.
Mark Stanley Personette, 80, was sentenced to life in prison on Wednesday for the sexual assault and murder of 15-year-old Marissa Harvey in 1978.
Investigators relied on DNA recovered from Marissa Harvey’s clothing and a piece of gum found on her body to identify, arrest and convict her killer.
Nearly two decades later, detectives turned to investigative genealogy, a forensic technique that compares DNA profiles with information in public genetic databases.
The approach allows investigators to construct an extended genetic profile and trace a suspect either directly or through biological relatives. It gained national attention after helping authorities identify the Golden State Killer in 2018.
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Using the technique, police identified Personette as a possible suspect in Harvey’s sexual assault and murder.
In 2021, FBI agents watched Personette discard trash in a Walmart parking lot more than 15 miles from his home.
The discarded material consisted only of personal hygiene products containing Personette’s DNA. Investigators later concluded that he had been keeping hygiene-related trash separate from his regular garbage.
Those newly collected DNA samples matched the genetic evidence recovered from Harvey’s clothing and the gum found on her back.
The match provided sufficient grounds for an arrest warrant and ultimately helped secure Personette’s conviction.
Investigators also found a 1970s map of San Francisco and California license plates bearing a 1979 registration sticker at Personette’s home. He nevertheless denied ever having visited the city.
Personette was arrested in 2021. He is shown in a 1979 booking photograph.
At Personette’s trial, another woman testified that he raped her in a wooded area of New Jersey in 1979, when she was 16.
At the time of Personette’s arrest, police said they believed he may have had more victims and urged law enforcement agencies across the country to review any unsolved sexual assault-related homicides involving young women.
The murderer’s sentencing was hailed by prosecutors in a statement released by the San Francisco District Attorney’s Office.
‘After almost 50 years, Mr. Personette is finally being held accountable for his heinous crimes against Marissa and will spend the rest of his life in prison,’ said District Attorney Brooke Jenkins.
‘While nothing can bring Marissa back to her family, today’s sentence hopefully leaves her family with a sense that justice was done for all that they have endured.’
