Michael Ackerman (Yellowstone County Detention Facility).
A septuagenarian Montana man will spend a relatively short time in prison for killing his wife, his stepson, and his stepson's girlfriend.
In January, Michael Joseph Ackerman, 74, pleaded guilty to counts of murder in the second degree and use of a firearm during a crime of violence, according to federal court records.
The plea agreement short-circuited a case over the September 2025 killings of Earlene Lucy Jones Ackerman, 65, Matthew Earl Black Thunder, 41, and Winona "Nona Sioux" Longee, 35.
This week, the defendant was sentenced to 15 years and six months in prison – a sentence substantially below what prosecutors requested but also a few years above what the defense asked for.
In a sentencing memorandum, prosecutors requested a sentence of 27 years and six months in federal prison. The plea deal did not take sentencing into account – instead only allowing the defendant to plead guilty to two counts total for the drug-fueled triple murder.
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.