ANAMOSA, Iowa (AP) — A 71-year-old inmate serving time at a maximum-security prison in Iowa has died of natural causes. The Iowa Department of Corrections says Carroll Duane Calhoun died Monday while in hospice care. Calhoun died of natural causes due to the final stages of chronic obstructive pulmonary disease. Hospice workers found that Calhoun had stopped breathing and officials with the Jones County Coroner’s Office later pronounced him dead.