Man Sentenced to Life for 1978 Murder After DNA on Chewing Gum Solved Cold Case

Mark Stanley Personette, 80, has been sentenced to life in prison for the 1978 murder of 15-year-old Marissa Harvey, a crime that went cold for over 40 years. The breakthrough in the decades-old case came through advanced DNA testing and investigative genealogy, which identified Personette as the suspect.

Harvey was visiting her sister in San Francisco when she disappeared after a planned day trip to Golden Gate Park. Her body was discovered the following day in Sutro Heights Park. Prosecutors stated she had been sexually assaulted, brutally beaten, and strangled.

Personette was arrested in Denver, Colorado, in December 2021. The San Francisco Police Department indicated that initial investigations in 1978 utilized the best available technology but could not identify a suspect. The case was reopened in 2021.

In the early 2000s, DNA analysis of evidence collected from Harvey’s clothing and a piece of chewing gum found on her back yielded a male DNA profile, but no identification. Nearly 20 years later, law enforcement employed investigative genealogy, a technique that compares DNA test results with public genetic databases to build a suspect’s genetic profile. This method was notably used to apprehend the Golden State Killer in 2018.

Using this technique, investigators identified Personette as a potential suspect. In 2021, FBI agents observed Personette discarding personal hygiene items in a Walmart parking lot. DNA from these items matched the profile found on Harvey’s belongings and the gum, leading to his arrest.

During Personette's trial, another woman testified that he had raped her in New Jersey in 1979 when she was 16. Investigators also found a 1970s map of San Francisco and California license plates with a 1979 sticker in Personette’s home, despite his claims of never having visited the city.

At the time of his arrest, authorities suspected Personette may have had other victims and urged law enforcement agencies nationwide to review unsolved homicides involving young women. San Francisco District Attorney Brooke Jenkins stated that Personette is now being held accountable and will spend the remainder of his life in prison, offering a sense of justice to Harvey's family.