Mistahimaskwa and fourteen of his companions were prosecuted in Regina for treason-felony. He did not participate in the conflict and tried to stop hostilities. However, according to the judge, Mistahimaskwa should have left his band at the beginning of the violence. The judge Hugh Richardson sentenced him to three years.
While incarcerated, Mistahimaskwa converted to Catholicism. After two years in the Stony Mountain Penitentiary, Mistahimaskwa was released (February, 1887), already ill. On January 17, 1888, he died on the Poundmaker Reserve. Since Mistahimaskwa never had a Reserve, his band became diasporic, dividing into other communities but continuing to maintain kinship ties.