During an arraignment Monday, Mark Kerrigan, 45, pleaded not guilty to assaulting his 70-year-old father, who died over the weekend after a disturbance at the family's Massachusetts home.
Middlesex County Assistant District Attorney Elizabeth Healy told CBS News that Mark indicated that he and his father Daniel had a violent argument that became "physical," and that he grabbed his father by the neck.
According to the police report, the argument was over the use of a telephone, and when police arrived at the home Sunday morning to find Daniel dead on the floor, Mark was noticeably intoxicated and belligerent when approached by officers.
"He refused to comply with their orders, and they had to subdue him with the use of pepper spray. He had to be forcibly removed from the home," Healy told CBS News.
Daniel's autopsy results will play a crucial role in the case.
"The question is, did the father die from a heart attack as the mother told the police, at least initially, or did he die because Mark Kerrigan put his hands on his father's throat, as he says, his father then fell to the floor and shortly after that died?" asks CBS News legal analyst Lisa Bloom. "So the cause of death is critical."
Mark Kerrigan has a long criminal history and was recently released from serving a two-and-a-half-year prison sentence, CBS News reports.