ST. PAUL, Minn. (AP) — A federal trial is underway for a Minneapolis police officer charged with perjury, falsifying records and civil rights violations by using excessive force.

Michael Griffin is accused of assaulting at least four people while off-duty after identifying himself as an officer, then filing false reports.

The incidents cited in the nine-count indictment date back to 2010 and 2011.

The indictment says Griffin was outside a Minneapolis nightclub in 2010 when his friend started arguing with a man who tried to walk away. It says Griffin followed the man, punched him until he lost consciousness, told officers to arrest the man and filed a false report.

The officer's attorney, Ryan Kaess, has said Griffin is innocent of all charges.