Michael J. Ackerman pleaded guilty after his wife, stepson and another woman were found dead in Poplar.

HELENA, Mont. — A 74-year-old Poplar man was sentenced to 15 years and six months in federal prison after admitting he killed his wife, his stepson and his stepson’s girlfriend in September on the Fort Peck Indian Reservation.

U.S. District Judge Brian M. Morris imposed the 186-month sentence after Michael J. Ackerman pleaded guilty to one count of second-degree murder and one count of using a firearm during a crime of violence. The sentence was below the 27 years and six months sought by prosecutors, but above the term urged by the defense. Ackerman also must serve five years of supervised release if he leaves prison.

The case grew out of the deaths of Earlene Lucy Jones Ackerman, 65, Matthew Earl Black Thunder, 41, and Winona “Nona Sioux” Longee, 35. Federal filings said Ackerman was in his home in Poplar on Sept. 11, 2025, when he and the others in the house had been using methamphetamine. Prosecutors said he came to believe the three were “setting him up.” A defense memorandum later called the case “a conundrum,” noting his limited criminal history and drug use, while also describing the killings as “a senseless act of violence fueled by methamphetamine and made easier by the use of a firearm.”

Authorities said the first report came early Sept. 14, when Yellowstone County sheriff’s deputies in Billings were told Ackerman had admitted killing three people. Deputies contacted him at a house in Billings. After they read him his Miranda rights, he agreed to speak with law enforcement. Court records said Ackerman told deputies he had been in a bedroom with Jane Doe 1 when she had a pistol in her hand. He said he picked up his Smith & Wesson 9 mm pistol and shot her twice in the head. Investigators later identified the victims by name in public reports.

Ackerman then told deputies he heard John Doe and Jane Doe 2 moving in the next room, according to court filings. He said he walked into the room where they were sleeping and shot them both. He told officers the bodies would be found inside his Poplar residence. Fort Peck Law and Justice Department officers went to the home and received no response. After getting a telephonic search warrant from Fort Peck Tribal Court, officers entered the home around 5:30 a.m. They found three bodies with gunshot wounds. Four 9 mm casings were found near the bodies, according to the government’s account.

The charging path changed as the case moved through federal court. Ackerman, also known as Michael J. Littlebull, first appeared in Great Falls in September 2025 on a complaint alleging three counts of second-degree murder. U.S. Magistrate Judge Timothy J. Cavan ordered him detained pending further proceedings. In January, Ackerman pleaded guilty to one count of second-degree murder and one count of using a firearm during a crime of violence. At the time of the plea, federal prosecutors said the murder count carried a maximum sentence of life in prison, a $250,000 fine and five years of supervised release.

The sentence landed between the two sides’ requests. Prosecutors asked for 27 years and six months, pointing to three deaths and the use of a firearm. The defense urged a shorter term and cited Ackerman’s age, lack of a serious criminal record and methamphetamine use. The defense also said the victims included Ackerman’s wife of 35 years, a stepson he had raised from an early age and the stepson’s girlfriend. The filings did not identify a clear motive beyond the drug-related belief that the victims were setting him up. Federal records also said Ackerman had worked as a plumber and had shown interest in running for tribal government office.

The investigation joined several agencies because the case began in Billings and led officers back to Poplar, a community on the Fort Peck Indian Reservation in northeastern Montana. Yellowstone County deputies handled the first contact with Ackerman in Billings. Fort Peck tribal officers obtained the warrant and entered the Poplar home. The FBI also investigated. Assistant U.S. Attorney Kalah Paisley prosecuted the case for the U.S. Attorney’s Office in Montana. Officials did not report that anyone else was suspected in the killings after Ackerman’s statements and the discovery of the bodies inside the home.

The court record leaves some parts of the case narrow and unresolved. The public filings describe Ackerman’s statements, the methamphetamine use, the pistol, the three deaths and the recovery of casings. They do not give a full account of what happened inside the home before the first shots were fired. They also do not say why Ackerman left Poplar before deputies reached him in Billings. What is clear is that the case ended without a trial after the guilty plea and the sentencing decision by Morris. Ackerman’s age means the 15-year, six-month term could keep him in federal prison into his late 80s.

For now, Ackerman remains under the federal sentence imposed in Montana. The next milestone in the case is the start of his supervised release if he completes the prison term and is released from custody.

Author note: Last updated June 29, 2026.