CBS News Correspondent Jerry Bowen reports that there was never any question that, with the help of a younger cousin, 17-year-old Mario Padilla used four knives and a screwdriver to stab his mother Gina Castillo to death.
Padilla, 17, was convicted Thursday by a Compton Superior Court jury. A separate jury convicted his cousin, Samuel Ramirez, 15, earlier this week but that verdict was sealed until Padilla's panel returned its verdict.
Jurors on Wednesday heard a 911 tape-recording of Padilla's mother gasping out to an operator: "My son, he's 16, he just stabbed me. I'm bleeding. Oh, I'm bleeding."
A defense attorney told jurors his client killed his mother in a "brutal and horrible crime," in opening statements for a case that has been linked outside of court to the slasher movie Scream.
"Mario Padilla killed his mother," attorney Paul Golub, representing the 17 year old, told jurors on Wednesday. "It was a brutal and horrible crime. I'm not going to sit here and say anything else."
But the lawyer did not suggest a motive. The movie Scream and its sequel, Scream 2, were not mentioned during the proceeding. The judge has ruled that no evidence relating to the films will be allowed at the trial.
There was the motherÂ's desperate 911 call as she lay dying and later, both boysÂ' confession to police Â– a crime that stunned neighbors in their working class Los Angeles suburb.
A family neighbor said, "He wasn't a gangbanger. But killing your mom... thatÂ's another thing."
Just as stunning was the motive. According to investigators, the boys said they needed money to fund a planned murder spree - a spree that would closely follow the story line of the two Hollywood Scream movies.
Investigators say the boys confessed to planning to buy costumes like those in the movie. And electronic voice boxes to conceal their identity.
Drew Barrymore starred in Scream. Transcripts from the preliminary hearing show that Padilla picked out a classmate he didn't know, but who closely resembled Barrymore, as one of his intended victims.
Psychologist Madeline Levine says, "You need a cat to copy. In this case, Scream is that cat."
Levine studies the effect of violence on children. She says the influence of movies like Scream makes children angrier and desensitized... and more likely to act out a violent impulse.
"There were a whole bunch of reasons why they acted out that way. But did the movie provide a blueprint? Absolutely," she continues.
This case was expected to become another showcase trial on the effect of violent films on teenagers. But the judge wouldnÂ't let it happen - barring any mention of the phrase or even the movies.
He also banneTV cameras, issued a gag order and suppressed all evidence, including material already made public. It was to be tried as a simple murder case.
Outside court, however, itÂ's one more exhibit in the case against Hollywood film violence. And there's another movie in this story. Investigators say the boys planned to base their legal defense on the film Primal Fear, in which a young killer was set free after faking insanity.
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