A confessed killer hugged one of the people he attacked Wednesday in a Douglas County courtroom shortly before a judge sentenced him to life in prison.

Laura Prince sobbed as she embraced her 16-year-old grandson Gevin Allen Prince, who had stabbed her shortly before he killed her mother with a kitchen knife and samurai sword in what a seasoned prosecutor described as a “horrific killing.”

“It will be OK, we’ll get through this,” Laura Prince told him.

Superior Court Judge Robert James sentenced Gevin to life in prison with the possibility of parole after the plea of guilty but mentally ill, for murdering Mary Joan Gibbs, 77, Aug 15, 2011.

Prince, clad in a khaki-colored jumpsuit, suffers from Asperger’s Syndrome, a mental condition that left him high functioning in some mental pursuits but often low functioning in social situations.

Laura Prince, who was raising her grandson, lived with Gibbs. District Attorney David McDade said Prince had a history of attacks on family members but the grandmother and great grand-mother had covered for him when police suspected he had once used a sword to stab the great-grandmother in the foot.

Systematic failures — juvenile authorities not proceeding against Prince and a failure to get adequate mental-health treatment because of insurance issues - frustrated David Cook, the teen’s uncle.

Cook said the household held a collection of 30 swords that belonged to another nephew who lived there. Cook said he thought the weapons had been removed after the previous attack, and he blamed other family members for allowing the weapons to remain.

“This was the most preventable murder in the history of the world,” Cook told the court and then addressed his nephew. “Gevin, you didn’t do this by yourself. You shouldn’t have been in that house. The swords and knives shouldn’t have been in that house.”

James also expressed frustration at the presence of the weapons despite Prince’s history.

“He is not totally to blame,” the judge said.

Prince will be eligible for parole in 30 years, said his lawyer, Travis Glahn.

Two neighborhood teenagers who tried to assist Gibbs after she ran wounded into her yard called 911 after Prince chased them off with the sword, McDade said. Gibbs warned them to flee, he said.

“She began to tell them to run, ‘He’ll kill you too,’” McDade said.

After chasing the teens, Gibbs returned and administered the death blow to his great-grandmother, driving the sword down into her head, McDade said.

When sheriff deputies arrived at the Spring Ridge Drive home, Gevin Prince was outside, holding both a sword and a loaded pellet gun. McDade said he stabbed his great-grandmother’s lifeless body to show the deputies that she was dead and they did not need to rescue her.

Deputies subdued him with a flash-bang grenade, a police dog which tackled him and a Taser. Prince fired several shots from the gun at deputies and struck patrol cars before he was taken into custody.

Laura Prince previously told the AJC she had reared Gevin and had tried to seek help for his mental problems, which is similar to autism, and the older he got, the more he “acted out” physically, eventually prompting 911 calls to county authorities.

On the day of the killing, Gevin wanted to use the computer, but his grandmother said no and Gevin became agitated, McDade said. He attacked his grandmother with a kitchen knife who fled to a bathroom and then attacked his great-grandmother who had come to assist her daughter, McDade said.