It was revealed that potential evidence for ongoing and future trials in Oakland, California, has disappeared, after a police sergeant gave testimony that a quarter of video clips from body-worn cameras was accidentally deleted two years ago during a software upgrade.

Sgt. Dave Burke was testifying last week in a murder trial of two men charged in July 2013 when he informed the court of the deletions, SF Gate reported.

"Though body-word camera footage is a minor issue in the case, Burke's testimony provided a glimpse into Oakland's handling of a nascent technology that has been adopted around the country as a tool of police accountability," the article says.

While in court, Burke said that none of the footage should have been lost from the system, as the settings were set to never delete. The department further stated through a spokesperson, Officer Marco Marquez, that he "did not know how many video files were deleted. But he said the department had not 'discovered any cases that have been affected by this incident,'" SF Gate reported.

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The deletions were a part of an upgrade to the Oakland Police Department's computer system in October 2014, which "stores dozens of terabytes of the body-worn camera footage."

Deputy District Attorney Butch Ford, who is prosecuting the murder case, explained to SF Gate outside court that instead of pressing "preserve everything," the IT employees checked a box marked "preserve," causing about a quarter of the content to be deleted.

The problem was discovered a month later, when officers noticed a issue when searching for a video they could not find, Burke explained. The deletions range back to 2009, when the department's body-camera program began.

While the footage would have only served as a footnote in the evidence of the present case, a Bay Area civil rights attorney, John Burris, told SF Gate that the deletions could pose issues in some cases.

"If an officer's conduct is being questioned, an attorney might want to view past interactions involving the officer, but wouldn't be able to get the footage because of the deletions," the article said.