CHARLESTON, S.C. -- Christopher Pittman's age troubled jurors who debated whether he should be convicted as an adult of two counts of murder for killing his grandparents with a shotgun when he was 12 years old.

"We don't intentionally hurt the ones we love. But I have an adult brain and you try to think about what a child was thinking," Christine Peterson, 54, of North Charleston, a juror who is the grandmother of a 12-year-old.

"I'm sure many of us had sleepless nights," she added.

In the end, after more than six hours of deliberating over two days, the jury on Tuesday convicted Pittman, who maintained the anti-depressant Zoloft made him manic and he couldn't tell right from wrong.

The prosecution countered he was simply angry at his grandparents for disciplining him for choking a younger student on a school bus. Following the slayings, Pittman burned the couple's Chester County home and drove off in their car.

"If Chris Pittman had been 25 we could have come to a decision much, much earlier. Because of his age it was very, very difficult," said Arnold Hite, the jury foreman and a Charleston Southern University professor who said he was speaking for himself.

Pittman was sentenced to 30 years on each count. Circuit Court Judge Danny Pieper ordered the sentences to run concurrently.

Pittman, now 15 and being tried as an adult, hung his head as the verdict was read.

"I know it's in the hands of God. Whatever he decides on, that's what it's going to be," Pittman told the judge. Thirty years was the minimum sentence Pieper could give; the maximum was life.

Pittman's father, Joe, told Pieper he supports his son even though the victims of the November 2001 shootings were Joe Pittman's parents.

"I love my son with all of my heart, as I did my mom and dad," he said. "And mom and dad, if they were here today, would be begging for mercy as well."

Later, Joe Pittman called on South Carolina Gov. Mark Sanford and President Bush to pardon his son. He said he is a Gulf War veteran and urged the officials to "give my son the benefit of the doubt."

Pittman's sister, Danielle Pittman Finchum, said on NBC's "Today" show Wednesday that her brother is not guilty and the family will keep fighting for his release.

"I think everybody failed him in some way or another. I mean, you can't go through life and not fail somebody in a certain way," she said. "We're going to fight for him and if I have to keep fighting for the next 29 years to get him out, he's not going to stay in there the full time that he's supposed to."

Peterson, the juror, said the jury was initially divided on the drug's impact as well as on the question of Pittman's youth.

"It bothered me a lot," she said. "It was not an easy decision. But everyone kept saying, 'Look at the evidence. Look at the evidence.' "

As for Pittman "I don't think he was a bad seed, I think he did crazy things as a boy growing up," Peterson said. "He didn't have a stable home life. But that doesn't excuse what he did."

"We're devastated. We're heartbroken. We're mystified the state chooses to treat a 12-year-old as an adult," defense attorney Andy Vickery told reporters later. "Is it consistent with our notion of decency ... to try 12-year-olds for murder?"

Prosecutor Barney Giese said he has sympathy for the Pittmans.

"Absolutely. I have sympathy for everyone in this case. It's a tragic case," he said. "But I also have sympathy for Joe and Joy Pittman."

Christopher Pittman was convicted of murdering 66-year-old Joe and 62-year-old Joy Pittman. He initially told police that a black man had shot his grandparents and burned the house and kidnapped him.

Prosecutors said they didn't think the Zoloft defense was viable.

"I really think that was a smoke screen," prosecutor John Meadors said later. "He just happened to be on an anti-depressant when this happened."

Zoloft is the most widely prescribed anti-depressant in the United States, with 32.7 million prescriptions written in 2003.

Pfizer, the manufacturer of Zoloft, issued a statement saying it was a tragic case and that the testimony showed Pittman needed help before the slayings.

"Zoloft didn't cause his problems nor did the medication drive him to commit murder. On these two points, both Pfizer and the jury agree," the statement said.

Last October, the Food and Drug Administration ordered Zoloft and other antidepressants to carry "black box" warnings -- the government's strongest warning short of a ban -- about an increased risk of suicidal behavior in children.

The case was one of the first in the United States in which a juvenile claimed the effects of an anti-depressant caused him to kill, Vickery said earlier.