Officials probe how mentally ill man got gun used in Alabama shooting BAY MINETTE, Alabama (Reuters) - Investigators in Alabama are trying to determine how a man with a history of mental illness obtained a gun he used to kill a sheriff's deputy and wound another when they responded to a 911 call at his trailer, a prosecutor said on Monday The man, 53-year-old Michael Jansen, initially opened fire from inside the trailer on Friday after three officers went to his home following a call from his mother that he was behaving erratically, according to police. Jansen was killed in the gunfight near the southern Alabama city of Fairhope. Police said the officers, standing outside, held a lengthy conversation with him before he came out and a close-range shootout ensued on the trailer's front porch. Jansen had been committed to a local mental hospital at least twice in recent years, said Lt. Jud Beedy of the Baldwin County Major Crimes Task Force. Federal law prohibits people who have been committed to a mental institution from buying guns through a licensed dealer, which are required to run a background check. District Attorney Hallie Dixon said Jansen may have legally bought the gun from an individual owner, allowing him to avoid the check. The Bureau of Alcohol, Tobacco, Fire and Explosives is working to trace previous owners of the gun to determine how Jansen may have acquired it, Dixon said. Reporting by Kaija Wilkinson; Editing by Kevin Gray, Bernard Orr