Witnesses offer differing accounts of how a verbal exchange between a Racine man and a Kenosha teacher escalated to violence, according to a criminal complaint.

But all agreed the two squared off, apparently ready to fight, before Martin L. Walker, 20, allegedly killed Colin Byars, 24, with a single punch.

Walker was charged Friday with felony murder while committing a battery, as a repeat offender. If convicted, he could spend an estimated 22 years in prison.

A $500,000 cash bond was ordered. However, even if Walker posted that money, it would not guarantee his release. Walker was on probation when Byars died, and likely will stay in custody while state officials decide whether to ask that his probation be revoked.

A criminal complaint filed Friday outlined accounts from one of Walker’s friends, one of Byars’ friends and an apparently neutral bystander who called 911 after the brief fight early Feb. 21 outside a Kenosha tavern.

A friend of Byars said she was at Big Shotz Tavern, near 30th Avenue and Roosevelt Road, with Byars and other friends. As the bar closed, they headed into the street.

The friend said she heard a group of men calling out behind her, asking if they wanted to go to an after-bar party. She ignored them and kept walking.

As Byars and another man reached the middle of 30th Avenue, the woman said three men confronted them; the woman was already across the street.

She said one man shoved Byars, then put up his fists. Byars also put up his fists, as if to fight. The woman couldn’t hear what the men said to each other, but she said she clearly saw the man land a single, “solid punch” to Byars’ face.

“Byars dropped his hands to his side, stumbled and fell to the ground hitting his head on the ground extremely hard,” the complaint says.

As Byars lay unconscious, the three men ran away.

A second female witness had a different account of the incident. The woman said she was leaving the bar with Walker, whom she knew as Duke, and others when she saw a man on a cell phone. Walker asked the man, later identified as Byars, where to find the after-bar party.

“Shut the f--- up,” Byars reportedly said.

“What did you say to me?”, Walker answered.

“You heard me,” Byars replied.

The witness said Walker took off his hat and coat and threw them on the ground. Walker and Byars then began circling each other, each with their fists up.

Byars took a swing at Walker, but missed, the woman said. Then Walker punched Byars once in the face. “It was a hard punch,” she said.

Walker and two other men ran away, but the woman said Walker later bragged about what had happened.

The third witness, a bystander, didn’t know the two men he overheard “squaring up” in the street as patrons streamed out of the bar. But, he said, it looked as if the two — one white man and one black man — were about to fight.

The witness was on his cell phone when he heard the white man say, “Just go away.”

It appeared to the witness that the white man was trying to back away when the other man threw the first punch, hitting him in the face. The witness said the man fell to the ground and appeared “helpless” as the black man walked up to him and punched him a second time.

The witness checked on the man and called 911.

Byars later died from a blunt force head injury.

Police suggested a charge of reckless homicide against Walker. That would have required prosecutors to prove Walker showed utter disregard for human life, that his actions created the risk of death or great bodily harm and that Walker was aware of that risk.

Under the murder charge filed Friday, prosecutors must show Walker caused Byars’ death while committing another crime.

In this case, that crime would be misdemeanor battery, a charge meant to address violence that falls short of causing broken bones or requiring stitches. A battery conviction could lead to a nine-month jail sentence.

Walker could be convicted of the battery-related murder charge, if prosecutors show the battery caused Byars’ death and Walker was responsible for that battery.

A hearing has been set for March 12 to decide if there is enough evidence to continue Walker’s case.

Meanwhile, on Thursday, a man sought in connection with Byars death surrendered to police.

Jeremy S. Powell turned himself in to the Racine Police Department for a probation violation warrant, Kenosha police said. Kenosha Police detectives went to Racine and interviewed him.

Powell is cooperating with investigators, police spokesman Sgt. Hugh Rafferty said. Charges have not been recommended against Powell in connection with the death of Colin Byars.