 The 20-year-old was glancing up at the roof several times, was using a range finder. Range finders are often used by marksmen to see how far their shots are. This caught the attention of the sniper so much that he took a picture of the 20-year-old, sent that up the chain of command. By the time that he had radioed for backup, noticed that the 20-year-old returned to the site where he ultimately took that position on the building with a backpack but had lost sight of him, and it was too late by then.