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Investigators Believe Presumed Killer Adopted His Brother’s Identity and a Transient Lifestyle to Evade Cold Case Murder Arrest for Decades

Abraham Rivera AKA Gregory Marc Riviera AKA Jon Paul

Abraham Rivera AKA Gregory Marc Riviera AKA Jon Paul

Juliette Rivera was only 25 years old when she was bashed in the head and killed near the unincorporated South Coast area of San Mateo County, Calif. Now, just over 30 years later, law enforcement claims to have identified her killer.

Justice, however, will prove elusive in the cold case murder.

The suspect, a transient man who went by the name of Jon Paul, passed away in January of this year. But, the alleged “Jon Paul” was not a man named “Jon” or “Paul” at all. According to the San Mateo County Sheriff’s Office, the killer had assumed his brother’s name and adopted a transient lifestyle in order to evade detection for decades.

It was mid-July in 1992, when a farmworker made the tragic discovery near an irrigation pond. Rivera’s body was in an advanced state of decomposition. She had been reported missing 10 days earlier.

An autopsy would show the victim died due to blunt force trauma from a flat object to the back and left side of her skull.

“Here at the San Mateo County Sheriff’s Office, a cold case does not mean a closed case,” Public Information Officer Lt. Eamonn Allen told Law&Crime. “We investigate all cases thoroughly.”

And investigators weren’t exactly empty-handed. They had a suspect and a name: Abraham Riviera. He was 50 years old at the time and a known acquaintance of the victim, according to the SMSCO.

The Alameda Police Department even had the suspect Riviera in their presence at one point. According to the sheriff’s office, the local police eventually decided they didn’t like his statement due to numerous inconsistencies — which means they did like him for the young woman’s murder. Picking up where Alameda police left off, San Mateo County Sheriff’s detectives came to the same conclusion and issued an arrest warrant for Riviera on Aug, 7, 1992.

But by the time he was charged, the man who also went by Gregory Marc Riviera was long gone. Detectives found his apartment in Alameda, Calif. abandoned.

The murder and subsequent escape was showcased on an episode of America’s Most Wanted soon thereafter.

The long-wanted, now-presumed killer was given an entry on a website, Northern California Most Wanted, that is run by the Northern California Regional Intelligence Center, aimed at enlisting the public’s help in finding individuals wanted by law enforcement.

Riviera’s entry notes:

On or about July 7, 1992, Gregory Marc Riviera, murdered his girlfriend, a 25 year old legal secretary named Juliette Rivera, who lived in the City of Alameda. Gregory Marc Riviera vanished shortly after Juliette’s body was discovered near Highway 1, South of Pescadero, CA. Please take into consideration that the photo of Gregory Marc Riviera is over 20 years old. Gregory Marc Riviera has a U.S. Army background; he has auto mechanic experience; he loves to talk about his times in Hawaii and has been described as a person who loves the Bay Area and likes to attend social events and local bars.

But it was only when the transient man who called himself “Jon Paul” died that the case came to a conclusion. The Merced County Coroner’s Office ran the deceased man’s fingerprints in order to locate his next of kin. Results showed those fingerprints actually belonged to Riviera. The SMSCO was contacted in May of this year.

According to the Half Moon Bay Review, the coroner’s office and detectives would later determine there is a man called John Paul – and that he’s still alive. That individual was identified as the brother of the deceased presumed killer. Officials eventually spoke with the man’s daughter, the paper reported, who said that her father and her uncle would often swap identities to keep law enforcement guessing.

“Based on this investigation with the identity of suspect Abraham Rivera AKA Gregory Marc Riviera AKA Jon Paul, finally located and now deceased, this case is closed,” the SMSCO said in a statement obtained by online news website

[image via Northern California Regional Intelligence Center]

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