CASA GRANDE, Ariz. (AP) -- Casa Grande police have arrested a man in the killing of a neighbor. Police said officers responding to a call Wednesday found 53-year-old Jeffery Zimmerman dead of an apparent gunshot wound to the head. According to police, officers immediately considered the death suspicious and that their investigation led them to determine it was a homicide. The investigation then resulted in the search of Jason West's residence and his arrest on suspicion of first-degree murder. Police so far said they haven't determined a motive for the shooting. Police said they didn't know if West has an attorney to comment on his arrest, and an online court docket does not yet list the case.