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DNA evidence spots suspect in 1970s San Luis Obispo County murder cases

San Luis Obispo County Sheriff's Office
The now-deceased Arthur Rudy Martinez (left) is the accused killer of Jane Morton Antunez (bottom) and Patricia Dwyer (top) in the late 1970s.

Law enforcement officials say they have solved a pair of 41-year-old San Luis Obispo County cold cases by identifying a suspect in two Atascadero murders with the assistance of DNA evidence. The San Luis Obispo County Sheriff’s Office announced Wednesday they consider the now-deceased Arthur Rudy Martinez as the killer of 30-year-old Jane Morton Antunez and 28-year-old Patricia Dwyer in the late 1970s.

Antunez was found in the backseat of her car on a dirt road with her throat cut and sexually assaulted in November of 1977. In January of 1978, Dwyer was found stabbed to death and sexually assaulted in her home. Both women were found with their arms bound behind them. At the time, the county sheriff’s office believed both women had been killed by the same person.

“Biological evidence was collected from both these scenes in 1977 and 1978,” Sheriff Ian Parkinson said at a press conference on Wednesday. “At the time, DNA evidence was technology that was not used in criminal cases.”

In 2009, a new California law began requiring law enforcement to collect DNA samples during felony arrests. Parkinson said this has created more than 2 million DNA profiles in the past decade. Detectives found a familial DNA match in that system to samples collected at the crime scenes in the late 1970s; meaning someone with DNA closely resembling the DNA collected at the crime scene was presently serving time for an unrelated crime. Investigators were able to determine the inmate had a relative living in Atascadero during the time of the murders: Martinez.

“We were already aware of Martinez as a suspect in this case by investigators in an earlier report,” Parkinson said. "There was [previously] no specific evidence linking him to these crimes.”

In 1977, Martinez was on parole in the county, but then moved to Spokane, Washington in 1978. There he committed multiple robberies and rapes, was arrested, and received a life sentence.

But in 1994, Martinez escaped from prison and according to the San Luis Obispo County Sheriff’s Office, lived for 20 years in and around Fresno.

Then in 2014, Martinez turned himself in to Central Valley authorities, allegedly for medical reasons.

“Because he was diagnosed with cancer and he could receive treatment in prison,” Parkinson said.

Martinez died in a Washington State prison less than two months later.

Following the discovery of the familial DNA, Parkinson said detectives were able to track down a sample of Martinez’s DNA at a former girlfriend’s house in the Central Valley. Then a witness to the 1977 murder of Antunez was able to corroborate the finding by identifying Martinez at the scene of the crime.

In additional to thanking San Luis Obispo County Sheriff's Office Detective Clint Cole for his work in solving the murder mystery, Parkinson said none of it would have be possible without advances in DNA technology.

“I really want to implore our governor that they need to put more money into DNA testing,” Parkinson said. “The amount of work these labs have on their plate is extremely significant. The importance of DNA to an early identification of possible suspects is something we would really benefit from.”

Parkinson said top priorities for his office are solving other cold cases, like the highly-publicized 1996 disappearance of Cal Poly student Kristin Smart and the 2009 murder of 71-year-old Jerry Greer in Templeton.

“Both of those are actively being investigated and will continue to be,” Parkinson said. “Our hope is to bring those to a resolution as well.”

Parkinson said his office worked with the Bureau of Forensic Services (BFS) regional laboratories in Richmond and Goleta, and the California Department of Justice's Bureau of Investigation office in Fresno.

Califonia Attorney General Xavier Becerra praised the San Luis Obispo County Sheriff’s Office for identifying a suspect in the Antunez and Dwyer murders. In a press release from the San Luis Obispo County Sheriff's Office, Becerra is quoted saying, “here in California we have the technology, we have the know-how, and we have the will to work together to take on criminals operating in our state.”

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