HELENA, Mont. (AP) — A lobbyist and former firearms safety instructor sentenced to more than three years in prison in October in the accidental shooting death of his hunting partner in Helena has requested a retrial alleging the judge was biased.

The Independent Record reports that District Judge Michael McMahon imposed a 20-year sentence on 62-year-old Gregg Trude with all but 1,272 days suspended in the death of Helena doctor Eugene “Buzz” Walton.

Authorities say Trude pleaded guilty in September to negligent homicide after acknowledging he placed a loaded rifle on the backseat of his truck before it accidentally discharged and killed Walton following a hunt in 2018.

Trude’s new attorneys say McMahon could not have been impartial because of his personal relationship with Walton, which he disclosed during the sentencing hearing.

Attorneys say McMahon made multiple comments during the sentencing including comparing Walton to his own father who died years earlier.

Attorneys have asked that Trude in separate motions filed Friday be allowed to withdraw his guilty plea and be released from Montana State Prison where he has served about 10 weeks of his sentence.