30-year-old cold case involving murder declared solved

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A murder case that went cold 30 years ago is now declared closed. 

25-year-old Juliette Rivera was reported missing to the Alameda Police Department on July 7, 1992. The APD launched a missing person investigation and spoke with Gregory Marc Rivera, an acquaintance of Rivera’s. 

According to investigators, they found “numerous inconsistencies” in Riviera’s statement and began to suspect him of being involved in Rivera’s disappearance. 

On July 17, 1992, a decomposed body of a young female was found by a farm worker in a rural area of unincorporated San Mateo County’s South Coast area. The body was later identified as Rivera. The autopsy revealed that Rivera suffered blunt force trauma from a flat object to the head. 

On August 7, 1992, SMC Sheriff’s Detective issued a warrant for Riviera in San Mateo County and was charged with the murder of Rivera. Riviera fled on July 29, 1992, and avoided law enforcement for 30 years. 

In May of 2022, the Merced County Coroner’s Office contacted the SMC Sheriff’s Office about a local man named “Jon Paul” who died on January 29, 2022. The coroner had a fingerprint analysis to locate next of kin, and it matched Abraham Rivera, also known as Gregory Marc Riviera. 

The MCCO found the warrant for Riviera’s arrest in San Mateo County. 

Further investigation reveals that Gregory Riviera had a brother named John Paul. According to John Paul’s daughter, John Paul is still alive and suffering from medical issues. She also told MCCO that Gregory and John Paul had used one another’s identities for 30 years to avoid law enforcement. 

The SMC Sheriff’s Office had confirmed the deceased man’s identity as Gregory Marc Riviera, and the case was declared close.