Gov. Jerry Brown signed the bill into law in September. By then, Fremont had purged decades of information.

Between June and December 2018, Fremont destroyed six batches of records covering investigations of police misconduct, citizen complaints and disciplinary files spanning 1971 to 2016.

It's unclear what specific information was contained in the files that Fremont destroyed. The contents of most of the files identified on several lists obtained by KQED through a public records request were not described in detail.

But certificates of destruction, which Fremont requires whenever a city record is purged, reveal that some recent cases involved investigations of officers for dereliction of duty, arrest by other agencies and misuse of police equipment.

One destroyed file was for a 2012 investigation into allegations that an officer “targeted” a person and carried out a false arrest. The officer was exonerated, according to a one-sentence description of the file, therefore it’s unlikely its contents would have been subject to disclosure under SB 1421.

However, brief descriptions of several other destroyed case records show that some officers were disciplined for misconduct, including multiple terminations. One destroyed record of a 2006-2008 investigation resulted in 11 orders to impose discipline against a police officer.

One category of records Fremont destroyed last year included audio recordings and paper documents related to “various IA (internal affairs) investigations” and “termination proceedings” for police officers from 1973 to 2005. Another file included “numerous documents regarding an officer’s policy violations and discipline,” from 1971 to 1975. A 1986 case file that was destroyed concerned one officer who was “surreptitiously recording other employees.”

The city also destroyed 11 boxes of “training review board” files that included information about officer-involved shootings and other serious incidents that occurred between 2003 and 2015. A training review board is convened as the first step towards investigating in-custody deaths and similar incidents. If the board discovers policy violations by officers, they refer the case to internal affairs for further investigation.

It’s unclear if any of the destroyed board files resulted in a full IA investigation. Since 2012, Fremont police have been involved in eight fatal shootings, according to data maintained by the state Department of Justice.

Police unions lobbied intensely against SB 1421, authored by state Sen. Nancy Skinner, D-Berkeley. Earlier this year, in a last-ditch effort to prevent the law from applying to records created before the statue took effect on Jan. 1, police unions sued to stop officers' employers from making records public. So far, the unions have lost in the courts.