1992 Peninsula Cold Case Closed

SAN MATEO COUNTY, CA — A wanted suspect in a 1992 Peninsula killing has been found dead, putting an end to a 30-year-old cold case, the San Mateo County Sheriff’s Office said.

The Juliette Rivera homicide probe concluded with the confirmation that the lone suspect in her killing had died, the San Mateo County Sheriff’s Office said Tuesday in a news release.

Gregory Marc Rivera, 50, was an acquaintance of the victim but they were not related.

Local authorities on May 12 were notified by the Merced County’s Coroner’s Office that fingerprints taken from of a transient “Jon Paul” who was found dead Jan. 29 matched the suspect’s, the Sheriff’s Office said.

Juliette Rivera was reported missing to the Alameda Police Department on July 7, 1992.

Gregory Marc Riviera made inconsistent statements during the investigation that led Alameda police to suspect his involvement in the victim’s disappearance, the Sheriff’s Office said.

A farm worker in a rural area of unincorporated San Mateo County South Coast area found Juliette Rivera’s body badly decomposed near an irrigation pond on July 17, 1992.

An autopsy showed she suffered blunt force trauma from a flat object to the left rear skull, the Sheriff’s Office said.

A warrant on suspicion of murder was issued in San Mateo County for Gregory Marc Riviera on Aug. 7, 1992, the Sheriff’s Office said.

Gregory Marc Riviera eluded law enforcement for 30 years after abandoning his Alameda apartment.

Detectives learned Gregory Marc Rivera had a brother named John Paul with whom he swapped identities to evade authorities, the Sheriff’s Office said.

“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 Sheriff’s Office said in a statement.

The Sheriff’s Office credited the Alameda Police Department, the Merced County Sheriff’s Office and Coroner Bureau, and the San Mateo County District Attorney's Office for assistance in the investigation.