A grand jury on Tuesday returned an indictment on two counts of first-degree murder against a 27-year-old Upper Marlboro man whom police have called a serial killer who is suspected in at least three other slayings.

Jason Thomas Scott was indicted in the deaths of Delores Dewitt, 42, and her 20-year-old daughter, Ebony, Prince George’s County State’s Attorney Glenn Ivey said. Their charred bodies were found March 16, 2009, in a burning car in Largo. That was just two months after another mother and daughter, 45-year-old Karen Lofton and 16-year-old Karissa, were found shot to death in their Largo home.