Harry Potter and the Order of the Phoenix
Sturgis is a member of the Order who first appears with that initial group of guards in Chapter 3. He is described as a "square-jawed wizard with thick straw-colored hair" (3.83). When Harry, Ron, and Hermione are supposed to head over to Hogwarts, Sturgis is on guard duty. But Moody complains that he never shows up. Later on, a Daily Prophet article announces that Sturgis has been arrested trespassing at the Ministry of Magic. He has "refused to speak in his own defense" and so is "convicted [...] and sentenced to six months in Azkaban" (14.85). Later still, we find out that Sturgis's apparent betrayal is actually the result of the Imperius Curse. Before discovering that prophecies can only be claimed by the people they're about, Voldemort forces innocent people into the Department of Mysteries to try and steal Harry's prophecy.