California prosecutors have filed new charges against a convicted kidnapper and rapist in connection with a 2015 abduction and ransom case with three victims in the Bay Area that cops had never been told had happened until he confessed to a small-town police chief who had no prior connection to any of the investigations, according to authorities.

Matthew Muller, 47, is serving a 40-year sentence for the kidnap and rape of a Vallejo woman in 2015. Her abduction was initially thought to be a hoax, cynically dubbed the “Gone Girl” kidnapping after the book and movie.

In the new case, which was not reported to police at the time, Muller allegedly kidnapped two unidentified men and a woman in San Ramon and held them hostage until one of them paid “tens of thousands of dollars” in ransom to release all three.

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Muller, a Harvard alumnus, Marine veteran and former immigration attorney, took the money and ran, according to prosecutors. The victims were so afraid that they never called authorities, and prosecutors say they still wish to remain anonymous. 

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Although the victims never contacted police, Seaside Police Chief Nick Borges obtained a confession from Muller in another bizarre twist in a case that has been full of them for years, a spokesperson for Contra Costa County District Attorney Diana Becton’s office told Fox News Digital.

Borges had invited the couple central to Muller’s federal kidnapping conviction to speak about how police gather evidence and interview victims. They were featured in a Netflix documentary about the harrowing “Gone Girl” case. After meeting them, Borges suspected Muller had committed more crimes and sent him a letter.

“That’s when Muller began confessing to additional crimes beginning in in 1993 when he was 16,” Ted Asregadoo, the DA’s public information officer, told Fox News Digital. “Over the course of their communication with Muller, a 2015 unreported kidnapping and ransom incident in Contra Costa County was mentioned by Muller.”

Borges shared the information with Contra Costa investigators, leading to the charges announced this week.

“The Contra Costa District Attorney’s Office has filed three felony charges of kidnapping for ransom against Matthew Daniel Muller, a convicted kidnapper and rapist currently serving a 40-year federal prison sentence,” the DA’s office said in a separate statement Monday.

“These new charges stem from a previously unreported 2015 crime in San Ramon, where Muller unlawfully held three victims captive and demanded tens of thousands of dollars for their release. This revelation came to light in 2024 after Muller confessed to multiple crimes in Northern California, including this incident in Contra Costa County.”

Becton’s office filed three charges of kidnapping for ransom in the San Ramon case.

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Her counterpart in Santa Clara County said last month that Muller is also now suspected in two home invasions in 2009. State-of-the-art forensic DNA testing led detectives to him in those cases, authorities said.

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But Muller allegedly also confessed to all three of the newly revealed crimes in letters he exchanged with law enforcement, according to prosecutors. 

“After learning of Muller’s confession, detectives from the Contra Costa County Sheriff’s Office initiated an investigation, despite the lack of a reported crime in 2015,” Becton’s office said in a statement. “The Contra Costa District Attorney’s Office joined the investigation on December 13th, 2024, which included a meeting with Muller.”

If convicted on the latest charges, he could face life in prison. He is serving his current sentence in a federal prison in Arizona, but is expected to return to California to be arraigned on the new charges. Becton’s office did not specify a court date.

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“The trauma of crime can have lasting effects that some people endure for their entire lives – whether the crime is reported or not,” Becton said. “Muller committed serious offenses throughout Northern California, and my office will be resolute in seeking justice on behalf of the victims in Contra Costa County.”

In the Vallejo case, Muller broke into a house and drugged a woman and her boyfriend. He tied up the female victim, brought her to a cabin in South Lake Tahoe, and sexually assaulted her. He held her for two days before driving her to Southern California and letting her go.

Fox News’ Stepheny Price contributed to this report.