Prosecutors charged a man with manslaughter Friday after surveillance video showed a 30-year-old man died after a single punch sent him to the ground in St. Paul.

Peter Nguyen, of Coon Rapids, was found unresponsive on the sidewalk outside the Far East Bar & Restaurant in Payne-Phalen on March 23 about 12:55 a.m.

He died soon after at Regions Hospital. The Ramsey County medical examiner’s office determined Nguyen died of a closed-head injury and ruled his death a homicide.

A witness told police that Nguyen “had some kind of issue with people who had been attending a birthday party at the bar” and was “squaring up to fight” with another man outside the bar at Arcade Street and Case Avenue, according to a criminal complaint.

Another man came up along the side of the man who Nguyen was going to fight and struck Nguyen with his fist, causing Nguyen to fall to the ground.

Through additional witnesses and surveillance video, police identified the man who delivered the punch as Pheng Vang, 38, of St. Paul, according to the complaint against Vang. Police interviewed Vang on Thursday and he said he was starting to leave the bar when “an argument began to escalate” on the corner and he walked up to defuse the situation, the complaint said.

Nguyen reached down to pick up his shot glass and Vang punched him once, striking him in the shoulder and face, the complaint continued.

Vang said he believed he was defending the man, who is a relative of his and who Nguyen was going to fight.

After Nguyen fell to the ground, Vang left the area.

The Ramsey County attorney’s office charged Vang with first-degree manslaughter while committing fifth-degree assault. An attorney wasn’t listed for Vang in his court file as of Friday afternoon.

Nguyen “played a huge part in taking care of my mother, brother, and little sisters,” a brother of his wrote on a GoFundMe fundraiser for his funeral and to help the family.

He said Nguyen “did his best and did everything he can to keep food on the table and roof over their heads.”