Residents of Lewiston, Maine spent two days sheltering in place as authorities searched for the man suspected of fatally shooting 18 people and wounding 13 others.Law enforcement has a playbook for capturing fugitives. But Maine's rural setting, the nearby international border with Canada and the suspect's military training all complicate the search.NPR's Ailsa Chang speaks with Kenneth Gray, who was a special agent with the FBI for 24 years, about what a search like this entails.Note: This episode was recorded on Friday afternoon, shortly before authorities lifted the shelter-in-place order for Lewiston and the surrounding area.Email us at considerthis@npr.org.