23-year-old Colten Towry is charged with having a deadly punch.
He is charged with manslaughter for causing the death of Derek Oshkeshequoam.
Mandan investigators testified this afternoon that Towry punched Derek once in the face, outside of a house party late last October.
The 30-year-old Bismarck man died two days later from his injuries.
A Mandan police officer testified to an interview with Towry about what happened.
"He told me at some point Mr. Oshkeshequoam hit him in the shoulder, that is when he stated he then got mad and then hit Mr. Oshkeshequoam who then stumbled backwards onto the ground." says Peter Czapiewski, Mandan Police Department.
One party-goer testified that he just thought Derek was knocked out from the fight, and passed out from drinking alcohol.
Derek was carried into the basement of the home, then dropped off at a local hospital the following day where he later died.
Towry told police that he was initially trying to break up a fight between Derek and another party-goer named Terry Olson.
"Did Mr. Towry mention Terry Olson kicking him in the head after he was down? Yes."
According to members of the Mandan police Department, there is a subpoena for Terry Olson, but he can not be located.
Two others are charged in the case.
34-year-old Christopher Vernon and 28-year-old Joseph Houle are charged with reckless endangerment.
Towry's trial is scheduled all week.