HILLSBOROUGH - On April 20, 1999, two teenagers killed 13 people at Columbine High School in Colorado before killing themselves. On the seventh anniversary of that massacre, Alvaro Rafael Castillo threatened to kill himself and was committed to UNC Hospitals.

On Thursday, the Hillsborough teenager stood accused of trying to pull off a similar attack after shooting his father in the family home.

Whether the April 20 dates are coincidence or intentional, they underscore Castillo's obsession with the killings in Littleton, Colo.

Comments on Castillo's MySpace account, writings found in his home, and the trench coat worn during the attack evoke memories of Columbine.

In a videotape received Thursday by The Chapel Hill News, Castillo is wearing a handmade T-shirt that says "Natural Selection," the same words that were on Eric Harris' T-shirt during the 1999 attack he launched with Dylan Klebold.

"I am obsessed with the Columbine Massacre," said the letter accompanying the videotape. "I know almost every detail."

On Thursday, Columbine's principal, Frank L. DeAngelis, said he had received e-mail from Castillo.

"Dear Principal," it began. "In a few hours you will probably hear about a school shooting in North Carolina. I am responsible for it. I remember Columbine. It is time the world remembered it. I am sorry. Goodbye."

In a letter to Columbine parents, DeAngelis said he read the message at 3:15 p.m. EDT and immediately notified the local Jefferson County sheriff's department, which called authorities in North Carolina. By that point, Castillo had been arrested.

"I regret any unwanted memories this brings up," DeAngelis wrote to parents. "We are all deeply affected by this unfortunate event."

Before his first court appearance Thursday, Castillo told reporters he had been obsessed with the high school massacre and he didn't know why.

On April 20, according to an involuntary commitment affidavit, Castillo told his father and other relatives that he was going to kill himself. "A shot gun was taken from him and [Castillo] left the house," the affidavit says.

Deputies found shotgun shells on Castillo before he was admitted to UNC Hospitals for eight days for "stabilization."

Soon after, he was discharged from the N.C. National Guard for being "medically disqualified." Castillo entered the Guard as a cook in 2004 but had never been deployed or gone beyond basic training, according to the statement.

On Wednesday, deputies found writings that Castillo composed.

According to a search warrant, officers seized a note left on the couch near Castillo's father's body, a diary and other note, and a notebook titled "Mass Murders and School Shootings of the 20th and 21st Centuries."

Copies of the movies "Zero Day," "Elephant," and "Bowling for Columbine," among other evidence also were seized.

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