A triple killing inside a Yellowstone County home ends with a sentence far below prosecutors’ request.
BILLINGS, MT – A 74-year-old Montana man who admitted to killing his wife, stepson, and his stepson’s girlfriend during a methamphetamine-fueled episode has been sentenced to 15 years and six months in federal prison, closing a case that stunned the community and left lingering questions about motive.
Michael Joseph Ackerman pleaded guilty in January to second-degree murder and use of a firearm during a crime of violence in connection with the September 2025 killings. The victims were identified as Earlene Lucy Jones Ackerman, 65, Matthew Earl Black Thunder, 41, and Winona “Nona Sioux” Longee, 35. The sentence handed down this week falls well below the 27 years and six months sought by prosecutors, though it exceeds the term requested by the defense.
Details of the killings and plea agreement
According to federal court records, the plea agreement allowed Ackerman to admit guilt to two counts without stipulating a specific sentence, effectively narrowing the scope of charges in a case involving three deaths.
Prosecutors outlined the events of Sept. 14, 2025, in a sentencing memorandum, stating Ackerman had been using methamphetamine in his home when he became convinced his family was “setting him up.” He then retrieved a Smith & Wesson 9mm pistol and shot his wife twice in the head.
The memo states he then entered another room where his stepson and Longee were sleeping and shot them both. Law enforcement was alerted after one of Ackerman’s adopted sons called authorities, reporting that Ackerman was driving after the killings. Deputies later detained him at the residence, where he confessed. Tribal law enforcement subsequently discovered the victims inside the home.
Defense and prosecution arguments
In its sentencing memorandum, the defense described the case as “a conundrum,” pointing to Ackerman’s lack of prior criminal history and the role of drug use in the violence.
“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.”
Prosecutors, however, argued for a significantly longer sentence, emphasizing the severity of the crime and the loss of three lives. The final sentence landed between both recommendations.
Court records also noted Ackerman had been working as a plumber at the time of the killings and had expressed interest in running for a tribal government position. The defense further stated, “To make this case all the more perplexing, Michael J. presents as a very warm person. Throughout this entire legal process, Michael J. has been polite and respectful.”
Ackerman will be subject to five years of supervised release following his prison term.