An 8-year-old girl, Mychelle Elizabeth Barton, was killed in her suburban Atlanta apartment in Stockbridge on the night of Wednesday, July 28, 1999. Her 11-year-old brother, Matthew, and their stepmother, 27-year-old Leigh Ann Vandiver Barton, were also killed in the same home. Barton, is described as having placed both children back in their beds, leaving a video game on Matthew and a stuffed toy on Mychelle.

Investigators found several notes at the scene, including a computer-generated letter in the living room in which Barton confessed to killing his wife and children. The note said the children were killed to spare them a lifetime of pain and described methods used to make sure they did not awaken. The next day, July 29, 1999, Barton carried out a shooting at two Atlanta day-trading firms that left nine people dead and 13 wounded, then died by a self-inflicted gunshot as police closed in at a gas station in Acworth.

Authorities identified Mark Barton as the sole suspect in the deaths of Mychelle, Matthew and Leigh Ann. His suicide prevented an arrest or trial. Investigators also considered him the primary suspect in the 1993 bludgeoning deaths of his first wife, Debra Spivey, and her mother, Eloise Spivey; Barton denied involvement in those earlier deaths in one of his notes.