The 28-year-old weapons enthusiast and self-proclaimed survivalist joined the Marine Corps in 1999 but was discharged a month later for fraudulent enlistment. Four years later, he tried to join the Samson Police Department, but couldn't complete some of the physical requirements at the state police academy.
Other jobs also didn't seem to suit him. He resigned from at least two - one at a metals plant in 2003, the other at a sausage factory just last week. Lists found in his home of people and places he felt wronged him included both businesses and some co-workers.
Though they have learned more about McLendon's behavior in the days before the shootings, authorities said Thursday they still don't know what set him off.
"I don't think anybody could have anticipated this by looking at him and interacting with him," said Coffee County District Attorney Gary McAliley. "But certainly he had a volcano inside of him."
Investigators said they found a two-page, handwritten letter in which McLendon admitted he had killed his mother and said he planned to commit suicide. He also mentioned a family dispute over a legal issue but didn't reveal plans to kill anyone else. McAliley said earlier that McLendon appeared to have had a dispute with family members over a family Bible, though he said he now believes there's no merit to that idea.
McLendon started his two-county rampage across rural southern Alabama by burning down the home he shared with his mother in the small, isolated community of Holley's Store near Kinston. Authorities said results of forensic tests have not yet determined when Lisa McLendon was killed, but they do know her son set her on fire on their couch before driving away.
In the remains of the house, investigators found dozens of soot-covered DVDs on how to commit acts of violence. McAliley said they appeared to be serious, not a joke, and included one about how to shoot into a moving car. One of the victims was driving when he was shot and killed.
After he burned down the home, he drove about 12 miles southeast to Samson and gunned down three relatives and the wife and 18-month-old daughter of a local sheriff's deputy on the front porch of his uncle's home. He turned his gun next door and killed his 74-year-old grandmother and sent panicked bystanders fleeing and ducking behind cars.
McLendon then drove off, spraying bullets and killing three more bystanders.
Police caught up with McLendon in Geneva, about 24 miles from his mother's home, at Reliable Products, the metals plant he quit in 2003. Following a shootout with police, he walked into the business and killed himself.
McLendon had a permit for two pistols he had with him during the rampage but no license for two assault rifles he used as he squeezed off some 200 rounds. He bought plenty of ammunition and magazines the day before the killings, authorities said.
People who spoke to McLendon before the shooting, including the unidentified confidant, knew he was despondent but did not feel he would turn violent, even though he spent his free time at the local firing range, said Jerry Conner, chief of the Alabama Bureau of Investigation. He had no criminal record and the only complaint neighbors had was that they were worried about their cows because he was constantly behind his home shooting.
The information investigators have gathered "gives a window into what happened," Conner said. "But this sort of violence and rage, it just boggles the mind."