SAN FRANCISCO — San Francisco District Attorney Kamala Harris and Police Chief George Gascón on Tuesday downplayed a news report that evidence of dozens of police officers’ misconduct and convictions has routinely been withheld from defense attorneys.

Gascón said he discovered soon after he became chief last Augustthat the police department doesn’t have a policy governing the screening of police witnesses and handing over any resulting Brady evidence to the defense. Around that time, he added, he initiated discussions with the DA’s office on the lack of a policy.