SAN DIEGO (CNS/CBS 8) - The San Diego County District Attorney's Office announced Friday that no charges would be filed against a former San Diego police officer who was accused of raping a woman in El Cajon.

Officer Art Perea was placed on unpaid leave following the woman's accusations in February, was suspended in February and has since resigned.

The woman, a 19-year-old Point Loma Nazarene University student, was treated at a hospital, where she told a physician that the officer and a woman had allegedly sexually assaulted her at a residence earlier that evening. Medical staffers then notified authorities, according to the El Cajon Police Department.

Tanya Sierra of the District Attorney's Office said prosecutors did not believe they could prove the case beyond a reasonable doubt.

"It didn't meet our burden of proof," Sierra said.

Perea worked vice and was part of an anti-graffiti task force.