The Douglas County teenager who allegedly sliced his great-grandmother to death with a sword is expected to plead guilty.

Gevin Allen Prince, 16, is charged with killing 77-year-old Mary Joan Gibbs in August 2011 when the two got into an argument over video games.

Prince is scheduled to enter his plea today at 9:30 a.m.

In November a jury declared Prince was mentally competent to stand trial.

That was the second competency hearing for the boy. The first ended with the jury deadlocked.

Even though Prince was found competent, he could still enter a plea of guilty but mentally ill. That means Prince could be held at a facility that specializes in treating inmates with mental issues. He is expected to be sentenced to life with the possibility of parole.

According to Georgia code, “‘mentally ill’ means having a disorder of thought or mood which significantly impairs judgment, behavior, capacity to recognize reality, or ability to cope with the ordinary demands of life. However, the term ‘mental illness’ shall not include a mental state manifested only by repeated unlawful or antisocial conduct.”

Family members have testified that Prince suffers from Asperger’s Syndrome. The Mayo Clinic defines the disease as a developmental disorder that affects a person's ability to socialize and communicate effectively with others.

Prince had gone through two mental evaluations before his trial. The psychologists for the Georgia Department of Human Services first found him competent to stand trial. But on June 20, a local psychologist disputed the state’s findings.

“The legal standard for competency to stand trial is whether the person is unable to understand the charges against him or mentally incapable of helping his lawyers,” WSB Legal Expert Ron Carlson says.

 “There is some mental history that might help the defense,” Carlson said. “That does not often result in avoiding a trial. That is because the defendant has the burden of showing his condition is so severe that he cannot help in his own defense.”

The teenager is being charged as an adult.

 “He’s charged as an adult because the Georgia Legislature has made it clear someone 15 years of age who commits this crime is charged as an adult,” Douglas Co. District Attorney David McDade said in 2011.

He faces three additional charges of aggravated assault for stabbing his grandmother during the tirade. Prince also, with his sword, chased two juveniles who tried to stop the attack.

Since his arrest, Prince has been locked up in an area away from other prisoners at the Douglas County Jail.