ELYRIA, Ohio – Although a teenager's obsession with a violent video game may have warped his sense of reality, the boy is guilty of murdering his mother and wounding his father after they took "Halo 3" away from him, a judge ruled Monday.

"I firmly believe that Daniel Petric had no idea at the time he hatched this plot that if he killed his parents they would be dead forever," Lorain County Common Pleas Judge James Burge said.

Nonetheless, Burge rejected the defense attorneys' argument that Petric, 17, was not guilty by reason of insanity.

The defense didn't contest that Petric shot his parents in October 2007 after they took the game away from him, but insisted that the teen's youth and addiction made him less responsible.

Petric may have been addicted, but the evidence also showed he planned the crime for weeks, said Burge, who found the teenager guilty of aggravated murder, attempted aggravated murder and other charges.

Prosecutors said Petric planned to kill his parents because he was angry that his father would not allow him to play the video game, in which players shoot alien monsters that have taken over the Earth.

On the night of the shooting, Petric used his father's key to open a lockbox and remove a 9 mm handgun and the game.

Mark Petric testified that his son came into the room and asked: "Would you guys close your eyes? I have a surprise for you." He testified that he expected a pleasant surprise. Then his head went numb from the gunshot.

Deputy prosecuting attorney Anthony Cillo argued during the trial that the teenager had planned to make it appear to be a murder-suicide by putting the gun in his father's hand.

Defense Attorney James Kersey said that when the teenager fled the grisly scene, he only took one item with him: the "Halo 3" game.

Bungie LLC, once part of Microsoft, developed the Xbox 360-exclusive Halo 3, and Microsoft owns the game's intellectual property. Microsoft declined to comment beyond a statement: "We are aware of the situation and it is a tragic case."