A gunman, allegedly angry over stock-market loses, killed 12 people and wounded 12 others before taking his own life in Atlanta on Thursday. Mark O. Barton, a 44-year-old day trader, killed himself after a five-hour manhunt. Police believe he also shot his wife, Leigh, and two children from an earlier marriage. A 9-millimeter pistol and a .45 caliber handgun were found near Barton's body and a computer-generated letter and three notes were found near his family members, authorities said.

  • Barton, a chemist who took on the high-risk life of an independent stock trader, also was a suspect in the 1993 bludgeoning deaths of his former wife and his mother, authorities said. He was never charged in those killings.