Donald Ray Coleman, 55, of Gun Barrel City, entered the Kaufman Wal-Mart March 22 and allegedly shot 59-year-old John D. Morgan, also from the Cedar Creek Lake area, to death, according to law enforcement officials.
The shooting led to the closure of the Walmart for the day after the shooting at about 10 a.m.
After killing Morgan, the gunman then shot himself in the head. He was transported to a Dallas hospital by helicopter in critical condition.
No one else was injured in the shooting.
Law enforcement officers said an ongoing feud about an unidentified female may have led to the shooting.
In January, Coleman turned himself in to the Henderson County Sheriff's Office after fleeing Gun Barrel City police for several days.
He was accused of threatening to shoot a woman during a domestic violence argument. The woman told police he beat her and tied her up.
After the assault, Coleman told the woman he planned to go to a friend's house and kill him along with her, according to the victim's report to police.