Michael Ackerman (Yellowstone County Detention Facility).
A 74-year-old man from Montana is set to serve a relatively brief prison term for the tragic deaths of his wife, stepson, and stepson’s girlfriend.
Earlier this year, Michael Joseph Ackerman admitted guilt to charges of second-degree murder and using a firearm during a violent crime, as revealed by federal court documents.
His plea deal effectively halted the legal proceedings concerning the September 2025 murders of Earlene Lucy Jones Ackerman, aged 65, Matthew Earl Black Thunder, 41, and Winona “Nona Sioux” Longee, 35.
This week, Ackerman received a prison sentence of 15 years and six months. This decision falls short of the 27 years and six months that prosecutors had advocated for, yet it exceeds the duration requested by the defense team.
In their sentencing memorandum, prosecutors had emphasized a desire for a longer sentence. The plea agreement, however, did not include specific sentencing terms, focusing merely on allowing Ackerman to plead guilty to two charges related to the triple murder, which was reportedly motivated by drugs.
The defendant’s public defender called the case “a conundrum” in the defense’s own sentencing memo – noting Ackerman’s “almost zero criminal history” and his use of methamphetamine.
“The victims include Michael’s wife of 35 years, a stepson he raised from an early age and his stepson’s girlfriend,” the defense memo reads. “There appears to be no motive, instead this was a senseless act of violence fueled by methamphetamine and made easier by the use of a firearm.”
On Sept. 14, 2025, the Yellowstone County Sheriff’s Office received a phone call from one of Ackerman’s adopted sons, according to the Billings Gazette. The defendant was driving after killing three people, the caller told law enforcement.
The government’s memo describes the murders, at length:
On that day, Ackerman was using methamphetamine in his home. He came to believe his family was “setting him up.” He picked up his Smith & Wesson 9mm pistol and shot his wife twice in the head. He heard her son and his girlfriend moving around in the next room, but when he walked into the room they were sleeping. He shot them both as they slept.
Deputies detained Ackerman at home and recorded his confession. Then, tribal law enforcement discovered the victims at the residence.
At the time of the slayings, the defendant was working as a plumber and had expressed interest in running for a tribal government office.
“To make this case all the more perplexing,” the defense sentencing recommendation goes on, “Michael J. presents as a very warm person. Throughout this entire legal process, Michael J. has been polite and respectful.”
If and when Ackerman makes it out of federal prison, he will be subject to five years of supervised release.