Cook, Frank Leon, b.1853.

Frank Leon Cook was born in Kalamazoo, Michigan, on February 24, 1853, the son of Hiram and Mary E. (Vining) Cook. In 1868 the family moved to Little Boulder in Jefferson County, Montana. In 1883 Frank married Mary E. Douglass. He later moved to the Bitterroot Valley, where he farmed.

Frank Cook was returning from a prospecting trip in the Black Hills when he was joined by Michael McAndrews and George "Scotty" Mavor. McAndrews shot and killed Mavor on September 4, 1877, near what is now the town of Basin, Montana. Cook helped in the apprehension of Mavor and testified against him at his trial. McAndrews was convicted in the Jefferson County District Court, and the conviction was upheld in January 1878 by the Montana Supreme Court presided over by Henry M. Blake. McAndrews was executed on March 1, 1878, at Radersburg.