West Des Moines police today released results of an autopsy on a three-year-old found dead at his family home. Officer Jim Barrett is a spokesman for the department.He says three-year-old York Martin died of strangulation and also had blunt trauma and contusions to the head and neck. Police have interviewed the father of the child, who’s charged with first-degree murder, but Barrett says cops won’t be releasing details of what he said. Thirty-seven-year-old Christopher Martin entered a “not guilty” plea during his preliminary court appearance. The child’s mother and four-year-old sister were in the home at the time and were unharmed. The boy was found dead after a 9-1-1 call about four Wednesday morning to the house in a residential neighborhood of West Des Moines.