1983 Cold Case Ends In El Salvador: Sonoma County Sheriff

NORTHERN CALIFORNIA — A decades-long homicide investigation that began on a rural Guerneville road in 1983 has ended after a transnational manhunt in El Salvador.

In a case without a courtroom trial, Sonoma County detectives confirmed the identity of the man they say killed Robert Pangborn 43 years ago.

Sonoma County Sheriff’s Office detectives closed the 1983 homicide case of 31-year-old Robert Pangborn after DNA testing identified Oscar Bolanos, 67, as the suspect in his sexual assault and killing.

Pangborn was discovered May 21, 1983 on Riverlands Drive, partially clothed with a fatal stab wound.

Investigators collected physical evidence at the scene, but they could not identify a suspect at the time because forensic DNA testing was not yet available.

Detectives preserved the evidence and reopened the case repeatedly as technology advanced, according to the Sonoma County Sheriff's Office.

Between 2010 and 2023, investigators submitted samples to the Santa Clara County Crime Laboratory and the Serological Research Institute, where analysts conducted additional DNA testing.

In 1992, Bolanos was arrested in Los Angeles County for the sodomy and sexual assault of a juvenile and was sentenced to state prison, according to the Sonoma County Sheriff's Office.

As part of that case, his DNA was collected and submitted to law enforcement databases. Following his release from prison, Bolanos was deported to El Salvador in 1994, according to the Sonoma County Sheriff's Office.

Sonoma County detectives worked with the U.S. Department of Justice, the Department of Homeland Security, and the Federal Bureau of Investigation to locate him. Authorities found no record of his return to the United States and ultimately tracked him to a village near the location listed on an early 1980s work visa application, according to the Sonoma County Sheriff's Office.

The Sonoma County District Attorney’s Office issued a murder arrest warrant after detectives presented their findings. Federal and international authorities prepared extradition efforts, but Bolanos died in El Salvador from what investigators said appeared to be natural causes while battling cancer.

Although Bolanos never stood trial, the Sheriff’s Office said they concluded the evidence establishes he "sexually assaulted and murdered Robert Pangborn."

The Sonoma County Sheriff’s Office said it continues to invest in cold case investigations, allocating $50,000 annually for DNA testing and maintaining a detective position dedicated to unsolved homicides. Officials said roughly 70 cold cases remain open, some dating back to 1967, as investigators continue to reexamine evidence and pursue new leads.

Sheriff’s officials credited the Sonoma County District Attorney’s Office, the Santa Clara County Crime Laboratory, the Serological Research Institute, the U.S. Department of Justice, the Department of Homeland Security, and the FBI for their roles in resolving the case.