Minneapolis police officer Michael Griffin pleaded not guilty in his first appearance in federal court Thursday on charges of beating four men in 2010 and 2011 and then lying about it during civil suits they filed against him.

Griffin, wearing a suit and saying only "Yes, ma'am" when answering U.S. Magistrate Judge Janie Mayeron's questions, was arraigned and then released on a $25,000 bond. He agreed to give up his passport and remain law abiding.

He walked out of the hearing with his attorney, Ryan Kaess, and the president of the Minneapolis police union, Lt. Bob Kroll.

Neither Griffin nor his attorney made any public comments outside the courtroom.

Griffin's next court date was set for July 22.

On Wednesday, Kaess said that Griffin had not broken the law. "My client steadfastly maintains his innocence of all charges," Kaess said. "He intends to vigorously defend himself against these false accusations and is confident that when all the facts are presented to a jury he will be found not guilty."

Subject of 22 complaints

Griffin, 40, has been the subject of 22 internal affairs complaints, only one of which has been sustained by the Minneapolis Police Department.

Griffin is charged in the nine-count indictment with depriving the men of their civil rights, falsifying reports and committing perjury in testimony in two lawsuits filed against him.

The suits resulted in $410,000 in payouts by the city to the litigants and their attorneys.

The allegations are among the most serious federal charges brought against Minneapolis police officers in recent years.

Griffin works out of the Police Department's Fourth Precinct, in north Minneapolis. He has been placed on paid home assignment since his indictment Wednesday, meaning he does not do police work and must be at home during his regular shifts.

The indictment identifies the people Griffin is accused of assaulting only by their initials, although their names are known because of suits filed against him and the city.

Indictment details 2 fights

The indictment describes a May 29, 2010, incident when Griffin was in a confrontation while off-duty. It says he followed Ibrahim Regai from the Aqua bar to the Envy bar in Minneapolis, knocked him out and later wrote a police report that falsely claimed Regai was the aggressor.

In the second incident detailed in the indictment, Griffin was off-duty when he confronted four men — Jeremy Axel, Matthew Mitchell, Keyon Cooley and a fourth person identified as "JR" at the Loop bar in Minneapolis on Nov. 5, 2011.

The indictment said Griffin struck three of the men, knocking one unconscious. After more police arrived, Griffin gave "false, incomplete and misleading information," resulting in Mitchell's arrest, the indictment said.

In depositions in both civil suits, Griffin embellished his accounts with more falsehoods, the indictment said.

Staff writer Randy Furst contributed to this report. Matt McKinney • 612-673-7329