Alvaro Castillo has pleaded not guilty by reason of insanity to all the charges against him.
His mental competency had been questioned because he's received treatment for mental issues over the past two years.
DA Jim Woodall said Monday when the trial began, Castillo shot his father seven times with a sawed-off shotgun.
Following the murder, investigators said Castillo, armed with pipe bombs, ammunition and two shotguns, showed up on the campus of Orange High School on August 30, 2006. He was able to get past school security and shoot into a window on campus. A bullet grazed one student and glass cut another before he was stopped.
Castillo's public defender said his client was severely mentally ill and Castillo thought God chose him to sacrifice his father and others.
He admitted to the crimes in video footage and police said he also talked about the shootings as he was being arrested.
Castillo told police, "He made me suffer all his life. Someone had to put him out of his misery" - an apparent reference to his father.
When an officer asked, "What did he do to you?"
Castillo replied, "He abused me and my family. He was abused too."
On Tuesday, claims that Castillo also told a sheriff's deputy to kill him were heard in court.
A driver's education instructor, who was a former state trooper, was at the school the day of the shooting and helped the school resource officer get Castillo in handcuffs.
"He asked him if anyone was with him he said 'no, I did it myself'," Barry LeBlanc said. "Then he started laughing and saying, 'kill me, kill me, remember Columbine,' a couple more times."
Investigators have said Castillo was obsessed with the 1999 Columbine, Colo., high school massacre and sent an e-mail to the Columbine principal before the North Carolina attack.
An investigator also took the stand Tuesday and showed off some of the weapons allegedly used by Castillo.
Since his arrest, Castillo has been at Central Prison awaiting trial.
Testimony in the case continues on Wednesday.