Officials have identified the man, who died on Monday after a 21-hour standoff with law enforcement, as Robert Jay Thomas II, 25, of Cut Bank.
In a Thursday news release, Fergus County Coroner R.J. Brown said an autopsy by a deputy State of Montana medical examiner that Thomas died of an "apparent self-inflicted gunshot wound."
Brown will conduct a coroner's inquest, which is required by law whenever someone dies during contact with law enforcement.
Thomas held off police for nearly 21 hours while holed up in a Havre bank after a police officer tried to pull him over for a traffic violation on April 6. Havre police reported that he then stopped the vehicle and ran away, making his way into the bank shortly after.
Havre Acting Police Chief Gabe Matosich said that officers from Havre and Great Falls were negotiating with Thomas when they heard a shot, and that no law enforcement officer fired a shot.
Thomas died that night at Northern Montana Hospital in Havre and an agent from the Montana Division of Criminal Investigation is conducting the investigation, Brown said.