Mark Barton was born on April 2, 1955, in Stockbridge, Georgia, to an Air Force family, and was raised in South Carolina. Barton attended Clemson University and the University of South Carolina, where he earned a degree in chemistry despite an ongoing drug habit. Back in Atlanta, he married Debra Spivey, and had two children, Matthew and Mychelle. The family moved to Alabama due to Barton’s job. Barton became paranoid and started distrusting his wife. He lost his job when his work performance started to suffer. He was caught sabotaging company data in retaliation for his firing and he served a short jail term. Back in Georgia, Barton got a new job and began an affair with Leigh Ann Vandiver, one of his wife’s acquaintances. In 1993, Spivey and her mother Eloise were bludgeoned to death. Barton was the prime suspect in the double murder, but was not charged due to lack of evidence. Barton married Leigh Ann in 1995. His mental health continued to deteriorate and he began to suffer from severe depressionand paranoid delusions. Mark Barton had received a $294,000 insurance settlement from his first wife’s death, and used the funds to finance his day trading career, preferring high-risk Internet-related stocks. In the month prior to his killing spree, Barton had lost $105,000, and Momentum Securities had cancelled his account.

On July 27, 1999, Mark Barton woke up early in the morning and bludgeoned Leigh Ann to death as she slept. The next night, he also beat his children Matthew and Mychelle to death. He covered them with blankets and left notes on their bodies. On July 29, he went to the offices of his former employer, Momentum Securities. Witnesses say that Barton briefly chatted with coworkers before suddenly pulling out two pistols and opening fire. He shot and killed four people and attempted to execute Brad Schoemehl, who was shot three times at point-blank range. Barton then walked to the nearby All-Tech Investment Group building and murdered an additional five victims. Barton left the scene before police could arrive. The police searched his house and found the bodies of his family and the notes that he had left with them, in which Barton vehemently denied responsibility for the deaths of his first wife and mother-in-law. An intensive manhunt ensued. Four hours after the All-Tech Investment Group shooting, Barton accosted and threatened a young girl in Kennesaw, apparently attempting to secure a hostage for his escape. The young girl escaped and called police. Responding police officers spotted Barton in his minivan and a chase ensued, culminating at a gas station in Acworth. As law enforcement attempted to apprehend him, Barton shot and killed himself.