Mike Ryan, 48, was the father of two teenage girls
Mike Ryan
Mike Ryan
| Credit: Bloomington Jefferson Jaguars Twitter

Police say that an argument inside a Minnesota bar Saturday night led to a physical altercation in which a revered girls hockey coach was killed.

Officers found Mike Ryan, the head coach for the Bloomington-Jefferson High School girls hockey team and father to two teenage daughters, just before midnight, lying on the pavement outside Herbie's on the Park in St. Paul, suffering from an apparent head injury.

Ryan, 48, was rushed to a hospital, where he remained in critical condition until his death Sunday afternoon.

A statement from St. Paul Police indicates "witnesses told officers that a physical confrontation had occurred on the bar's front steps, during which the victim fell and hit his head."

According to the statement, Ryan's alleged assailant, 43-year-old Ryan John Whisler, "left the scene" after the coach's fatal fall.

Whisler, police confirm, turned himself in Sunday. He has been charged with second-degree unintentional murder.

Citing the criminal complaint against Whisler, the Duluth News Tribune reports that the initial argument inside the bar's started in the bathroom.

Ryan John Whisler
Ryan John Whisler
| Credit: Ramsey County Sheriff’s Office

"Whisler punched a hole in the cellophane" that had been placed over the urinals to encourage social distancing, and "took a cellphone video of himself urinating at the covered urinal," the complaint alleges, according to the paper.

Ryan, the complaint alleges, "was agitated with Whisler, but he didn't say anything to Whisler at the time." Later on, though, the complaint contends Ryan purportedly "called Whisler out for his behavior in the men's bathroom as they were leaving the bar, which led to a verbal confrontation."

The paper reports that police reviewed surveillance video captured outside the bar that allegedly shows Whisler grabbing Ryan's shirt before striking him, knocking his face covering off.

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A man with Whisler got between the two men, according to the complaint. Whisler then punched Ryan's "head with a large, sweeping motion," the complaint alleges. "The video, when played frame by frame, shows Whisler pushed [Ryan] towards the stairs. [Ryan] flew through the air to the bottom of the stairs and his head hit the concrete."

Medical examiners have deemed Ryan's death a homicide.

Whisler has yet to plead to the charge, and remains in custody on $500,000 bond.

PEOPLE could not reach Whisler's lawyer, Ryan Garry, for comment.