On videotapes and in journal entries chronicling his darkest thoughts, Alvaro Castillo expressed remorse more than once.
Jurors deciding the 22-year-old's fate, though, will be asked to determine whether the mentally ill man could tell right from wrong when he shot his father and opened fire on his former high school.
On Friday, the 10th day of testimony, much of the discussion was about what Castillo meant not only when he described his sadness and regret, but when he asked for forgiveness from God.
Psychologist James H. Hilkey and Dr. James Bellard, a forensic psychiatrist, both expert witnesses for the defense, testified that Castillo had an inkling that his actions were illegal. But, they added, he thought he was carrying out a higher calling from God. He spoke of "sacrificing" his father and Orange High School students and saving them from a future of temptations, sexual urges, taxes and other things he believed to be the ills of society.
Defense lawyers say Castillo cannot be held criminally responsible for his actions on Aug. 30, 2006, because his mental illness was so debilitating he could not distinguish between right and wrong.
District Attorney Jim Woodall contends otherwise. He pointed to Castillo's own words and those of his mother as evidence the then-19-year-old knew the difference.
Investigators found a note written by Castillo, a Catholic, on his bedroom door after he shot his father, Rafael Castillo.
"I am sorry, sorry for everything I did," the note said. "I am sick, mentally ill."
Hilkey and Bellard testified Friday that those words had more global meaning, that the defendant was sorry for many things.
"Everything literally means everything," Hilkey told Woodall on his cross-examination. "And in Mr. Castillo's mind there are many things that he thinks he has done wrong."
In his journal, Castillo mentions baby-sitting for a boy and becoming sexually aroused. His questions about his sexuality troubled him, and he was conflicted by his love for and fear of his father.
Castillo's mother reported after the shooting that her son had told her that after he killed his father he covered him with a sheet, kissed his hand and asked for forgiveness from his dad and from God.
In a video prepared for the media after the incident, Castillo said, "I did the most horriblest thing I could do."
Woodall tried repeatedly Friday to get Hilkey and Bellard to acknowledge that such words and actions were evidence Castillo knew what he did was morally wrong.
But neither conceded that point. Each described him as a complicated, delusional person.
Castillo, Bellard testified, thought God had saved him from his suicide attempt in April 2006 for "some specific greater purpose."
In the next months, his focus was on planning a school shooting similar to the mass shootings at Colorado's Columbine High School to relieve students from sin.
Castillo told mental health workers that he saw many signs from God between April and August of that year.
For example, in the Wal-Mart, where he bought ammunition, Hilkey said, Castillo saw a magazine clip similar to one used at Columbine and interpreted that as a sign from God.
The defense wrapped up its case late Friday.
Castillo, who has been quiet throughout the proceedings, stood when Judge Allen Baddour asked him whether he understood he could take the stand in his defense if he chose. Baddour told him that he would instruct the jurors that his decision not to take the stand could not be held against him during their deliberations.
James Williams, the chief public defender, spoke briefly with Castillo and then the defendant told the judge he had no concerns.
The district attorney will bring in rebuttal witnesses to the insanity defense early next week.