Valentine’s Day is usually about overpriced roses and mediocre dinner reservations. But for Art and Lois Serrin, February 14, 2007, became a waking nightmare that didn't end for over a decade. They walked into their daughter’s condo in Carlsbad, California, expecting a quiet visit. Instead, they interrupted a monster in the middle of a horrific act.
The man they saw in that bedroom wasn't identified for eleven years. He was just a shadow who walked past them and vanished into the night. It wasn't until 2018 that the world finally learned the name David Mabrito, the man responsible for the death of Jodine Serrin.
Honestly, the details of this case are the kind of thing that makes you want to double-check your locks twice. Jodine was 39 years old. She was a high-functioning woman living with mental health challenges, someone who loved nature and was active in her community. She lived in a condo on Swallow Lane, a place where she felt safe and independent.
The Night Everything Changed
When Jodine didn't answer her phone that night, her parents got worried. They had a key. They let themselves in. The lights were low. They walked toward the bedroom and saw a man they didn't recognize.
He was partially dressed. He was in bed with Jodine. In that split second, Art Serrin thought he was witnessing his daughter being taken advantage of, but he didn't realize the sheer scale of the violence. He told the man to get dressed and leave.
The parents waited in the living room. They were giving their daughter "privacy" to get dressed and explain who this stranger was. They waited. No one came out. When Art finally walked back into that room, the window was open. The man was gone.
And Jodine was dead.
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The level of brutality was staggering. An autopsy later confirmed she died from blunt-force trauma to the head. The killer hadn't just murdered her; he had "desecrated" her, a term police use when a crime goes beyond just taking a life.
Who was David Mabrito?
For years, the case was a complete brick wall. Police had DNA from the scene—it was all over the place—but no matches in the system. The killer wasn't a "known" criminal with a record in CODIS.
David Mabrito lived a double life that sounds like a cliché until you realize it’s real. He met his long-term partner, Marisa Patti, on a beach in Oceanside back in 1995. To her, he was a partner, a father figure to her son, and a regular guy who went to work every day.
He wasn't some shadowy figure lurking in alleys; he was the guy living next door.
But there were cracks. In 2011, Mabrito found himself in a weird situation. A police officer thought he matched the description of a suspect in a local bank robbery. They didn't arrest him for the robbery, but they did take a DNA swab.
Shortly after that interaction with police, David Mabrito died by suicide.
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He took his secrets to the grave. Or so he thought.
The DNA Breakthrough
Cold cases usually die because the trail goes cold, but technology caught up to David Mabrito. In 2017, the Carlsbad Police Department teamed up with Parabon NanoLabs.
They used "DNA phenotyping." Basically, they take the raw genetic code and predict what a person looks like—eye color, hair color, skin tone, even face shape. They released a composite image that looked eerily like a real person.
Then came the big guns: investigative genetic genealogy. This is the same technique used to catch the Golden State Killer. They took that DNA and uploaded it to public databases like GEDmatch.
They didn't find David. They found his relatives.
By building a massive family tree, investigators narrowed it down to one man who was in the right place at the right time. When they finally tested the DNA swab taken from Mabrito back in 2011 against the evidence from Jodine’s bedroom, it was a perfect match.
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The mystery was over. But for the families involved, the "closure" was complicated.
The Aftermath for the Families
Think about Marisa Patti for a second. She spent over two decades with this man. She shared a bed with him. She trusted him. Then, years after he’s gone, the police knock on her door and tell her he was a brutal murderer who killed a woman on Valentine’s Day while her parents stood in the next room.
That’s a different kind of trauma.
The Serrin family finally got their answer, but they didn't get a trial. There was no courtroom confrontation. No chance to ask why.
David Mabrito was described by some as a transient at times, but he clearly had the ability to mask his darkness well enough to maintain a long-term relationship. It’s a chilling reminder that you never truly know what’s going on in someone else’s head.
Lessons from the Jodine Serrin Case
This case changed how local departments approach cold cases in California. It proved that even a "dead" lead can be revived if the physical evidence is preserved correctly.
- DNA is King: If you have biological evidence, the case is never truly "unsolvable." Technology is always evolving.
- Genetic Privacy: This case highlights why people are often urged to opt-in to law enforcement searches on genealogy sites. Without those distant cousins sharing their data, Mabrito might never have been caught.
- The Double Life: Violent offenders aren't always "monsters" 24/7. They can be coworkers, boyfriends, and neighbors.
If you're following cold cases or interested in how these mysteries get unraveled, the best thing you can do is support organizations like Season of Justice. They provide funding for advanced DNA testing that small-town police departments often can't afford.
You can also check your own settings on sites like GEDmatch or FamilyTreeDNA. If you want to help solve cases like Jodine's, make sure your profile is set to allow law enforcement access. One distant match is often all it takes to bring a killer out of the shadows.