The Casper man accused of killing a University of Wyoming student in a Halloween brawl last year has pleaded guilty to a manslaughter charge.

Twenty-one-year-old Dalton Dale Williams pleaded guilty before Albany County District Judge Jeffrey Donnell today. In exchange for his guilty plea, prosecutors have agreed to drop the alternative charge of murder in the second degree. Prosecutors will also recommend a charge of three to five years of incarceration followed by a placement in a boot camp program.

Prosecutor Kurt Britzius told Donnell that Williams, who was twenty years old at the time of the incident, attended a party in Laramie on Halloween night 2014. A friend of Williams was in an altercation when the victim, twenty-one-year old Joseph McGowan, began walking toward Williams. Britzius said Williams voluntarily struck McGowan, acting in the “sudden heat of passion.” The fall caused McGowan to hit his head on the sidewalk resulting in injuries that later caused his death.

Defense Attorney Thomas Smith of Casper told Donnell that Williams “just reacted and struck Mr. McGowan.” He did not dispute that Williams caused McGowan’s death.

Williams told Donnell that he punched McGowan as a reaction to his walking toward him, and admitted that McGowan had not made any threatening motion to warrant the hit.

“I reacted to him, at a fast pace, walking towards us, and I heard him yell ‘Hey’ and I reacted,” he told Donnell.

Donnell said that the incident was a “genuine tragedy” for all involved. He said that Williams acted in violence toward a man who “barely even acknowledged” his presence.

“I would be interested in what you thought you were doing to so lightly do something like that,” he said to Williams.

Donnell noted that this was one of two similar incidents that occurred on Halloween night.

“This kind of unprovoked, thoughtless assault—this kind of stuff has got to stop,” Donnell said.

Donnell told Williams that he would take the prosecution’s sentencing recommendation into consideration, but warned him that he faces a maximum penalty of up to 20 years of imprisonment and a $10,000 fine.

Williams is currently released on a $100,000 signature bond. His sentencing will take place in 60-70 days. An exact sentencing date has not been set.