An Iraqi war veteran had post-traumatic stress disorder, his lawyer says, and killed his girlfriend because he thought she was part of a terrorist attack on America.

Davon Londell Thomas, accused of killing his 23-year-old girlfriend in November 2009, on Tuesday pleaded not guilty by reason of insanity.

Tigist Yemane, who originally came to Charlotte from Ethiopia for an operation to fix a heart defect, was shot to death in Thomas' parents' house in the Reedy Creek community. Police have said Thomas shot Yemane several times.

Defense attorney Jean Lawson, in a court document filed in Mecklenburg Superior Court, put prosecutors on notice that Thomas intended to raise the insanity defense.

"Davon Thomas volunteered to serve in the North Carolina Army National Guard, was deployed to active combat duty in Iraq and developed Post-Traumatic Stress Disorder," Lawson wrote in the document.

"At the time of the offense, Davon Thomas was in a delusional state and believed that a terrorist attack on the people of the United States of America had commenced and that the deceased was a member of a hostile military force whom he was obliged to kill."

Lawson called post-traumatic stress disorder a mental illness.

Read the complete story at charlotteobserver.com