Police think they’ve caught the serial killer who killed two mothers and daughters in Maryland and attempted to conceal his crimes by studying forensic science books. He intentionally killed the women in ways to confuse investigators, police say, fooling them into thinking the deaths were unrelated. The man, 27, holds two master’s degrees and is being held on federal weapons and sex charges—and hasn’t been charged with the killings. Police haven’t released his name, but predicted an indictment by the end of July. He is suspected in the deaths of Dolores and Ebony Dewitt, 42 and 20 years old, in March 2009, and of Karen and Karissa Lofton, 45 and 16, in January 2009. The Dewitts were found in a burning stolen car; the Loftons were shot in their home. Investigators are also looking into whether the man was involved in the 2008 death of a woman who was shot and whose home was torched—as well as other crimes around Washington and in Texas and Florida.