The search for an autistic 11-year-old boy in eastern Nebraska grew more dire Thursday as the boy remained missing for a third day and officials moved the search to nearby bodies of water. Ryan Larsen has been missing since Monday morning, when he walked out of his elementary school in La Vista, which lies just southwest of Omaha. Police say the child has a history of hiding from his family and authorities. La Vista Police Chief Bob Lausten tells the Omaha World-Herald that police have had to find the boy at least half-a-dozen times, but that he’s never been missing for days at a time. Lausten also noted that Ryan has been without his medication since he's been missing.