SAN FRANCISCO — The San Francisco district attorney’s office is combing through files in 1,400 cases — the entire universe of open narcotics cases in the office — to determine what can be saved and what needs to be dumped in the wake of an expanding scandal emanating from the police crime lab, a spokesman for the office said Monday.

“We’re going through the police records that we have, test results, we’re assessing everything,” said Assistant District Attorney Brian Buckelew. “There’s a taint here on this evidence. We’re going to do the right thing and we’re going to do it the right way.”