After hearing from a man whose beating at the hands of Michael Griffin left him bloodied and unconscious, prosecutors in the trial of the Minneapolis police officer on Wednesday summoned to the witness stand other people who saw the attack.

The witnesses — Jerry Berry and Mark Hillestad, who both worked at the Aqua nightclub at the time of the incident — testified before a federal jury in St. Paul. They were present the morning of May 29, 2010, when, shortly after bar-close, the off-duty officer confronted Ibrahim Regai on a crowded downtown sidewalk outside Envy nightclub.

Many of the details from that night previously emerged in a lawsuit that Regai filed against Griffin and the city of Minneapolis.

Griffin, a 10-year veteran of the department, is standing trial for perjury and deprivation of civil rights in connection with a pair of assaults, 18 months apart, which federal prosecutors allege Griffin used his position as a police officer to commit and attempt to cover up. He remains on home assignment after being relieved of duty.

The May 2010 confrontation occurred after an argument outside Aqua Nightclub and Lounge between Regai and Griffin's friend Justin Charpenter. After a few minutes, Griffin intervened by pulling out his badge and telling Regai to leave. On this much, both sides agree.

But the near unanimity that the witnesses expressed in describing the moments leading up to the assault melted away when lawyers on both sides asked about the incident itself.

Berry said Wednesday that Regai, whom Berry knew as a part-time bouncer at the since-shuttered Envy nightclub, had calmed down by then and was walking away.

"I was saying, 'You need to keep it moving, you don't need this,'" Berry said, in describing to jurors how he had tried to steer Regai away from the confrontation.

Berry told jurors that after Griffin followed them to Envy, Regai approached the officer in a nonthreatening manner, with his hands up, and said something to the effect of: "Why are you following me, man? I don't want to fight you."

Security camera footage played in court appears to show Griffin knocking Regai to the ground with a punch, and then a crowd forming around the two men. Regai, who said he blacked out for about 30 seconds, testified Tuesday that he went to a hospital that night for stitches to close a large gash on the back of his head from where he hit the sidewalk, as well as a split lip.

Hillestad testified that the officer did "a victory dance" in the street after knocking Regai out, a claim that the defense vigorously denied.

In his cross-examination of Berry, Griffin's attorney Robert Richman openly questioned Berry's recollection of the moments leading up to the assault and of the incident itself. He also questioned his credibility as a witness.

Charpenter testified Wednesday that Griffin handed him his badge before pursuing Regai, who by then was walking toward Envy. Regai, Charpenter told the jury, kept trash-talking as he walked. He testified that Griffin attacked Regai only after being provoked by the other man.

Griffin faces nine criminal counts in an indictment that charges him with depriving the men of their civil rights, falsifying reports and committing perjury in testimony in two brutality lawsuits filed against him. He has pleaded not guilty to all the charges.

The Envy incident is one of two assaults involving Griffin, 18 months apart, at the heart of the government's case.

In the other, on Nov. 5, 2011, prosecutors allege Griffin confronted four men — Jeremy Axel, Matthew Mitchell, Keyon Cooley and another man at the Loop Bar. Prosecutors allege that Griffin grabbed Cooley outside the bar, "flipped him to the ground … kicked [Mitchell] in the chest and punched [Axel] in the head from behind, rendering [him] unconscious." When police arrived, Griffin gave "false, incomplete and misleading information, resulting in Mitchell being arrested for obstructing a police officer with force," the indictment said.

Those witnesses will be called to testify later in the two-week trial.

Libor Jany • 612-673-4064 Twitter:@StribJany