COLUMBIA -- A judge on Tuesday ordered a new trial for a South Carolina man who blamed the antidepressant Zoloft after the then 12-year-old shot his grandparents to death and set their home on fire. Circuit Judge Roger Young said Christopher Pittman's defense team made several errors, including not pursuing a plea deal. Young presided over a three-day hearing last year to determine if Pittman, now 21, should get a new trial in the 2001 deaths of his grandparents. Pittman shot Joe and Joy Pittman while they slept, set fire to their home in Chester, about 50 miles north of Columbia, then took off in the family car. The boy initially told police a black man killed his grandparents and set the fire. He later admitted to the crimes, saying he shot his grandparents because they disciplined him after a fight on a school bus. At his 2005 trial, Pittman's attorneys argued the prescription drug Zoloft caused him to become manic and commit the slayings. Pittman was convicted on two counts of murder and sentenced to 30 years in prison. He has lost appeals to the South Carolina and U.S. Supreme Courts. Prosecutors said Pittman's actions like setting fire to his grandparents' home showed he knew the killings were wrong. Zoloft manufacturer Pfizer Inc. said after the verdict that Zoloft "didn't cause his problems, nor did the medication drive him to commit murder." A year after Pittman's trial, federal drug authorities began requiring 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, but not about potential homicidal risks. In last year's hearing, Pittman took the stand for the first time, saying his chief attorneys - lawyers who specialized in suing pharmaceutical companies - told him they were convinced the jury would blame Zoloft for the killings. He also said they never told him jurors in South Carolina could both blame the drug and find him guilty of murder. "I wasn't told even if Zoloft was a part in my crime, I still could be found guilty, and I was looking at 30 years to life. With the plea bargain, I could have gotten a lot less," he said then. Young agreed, citing Pittman's testimony and pointing out that defense attorneys also didn't tell a lawyer appointed as Pittman's guardian ad litem about the possibility of a deal. "It is clear Pittman's defense team did not appreciate how unlikely the 'Zoloft defense' would result in an acquittal of Pittman for the murders," Young wrote. "As a result, it is clear the defense team did not seriously pursue negotiations for a plea to voluntary manslaughter." If he had pleaded guilty to voluntary manslaughter, Pittman could have received a sentence of two to 30 years, at the judge's discretion. With a murder conviction, he faced a mandatory minimum of 30 years, with no possibility of parole. No new trial date has been set. Attorney General Henry McMaster's office defended the state's case at the 2009 hearing, and a spokesman said prosecutors had already begun drafting an appeal. Janet Sisk, an advocate who visits Pittman weekly at a Columbia prison, said she will discuss the good news with him Saturday. "I thought I was going to scream and pass out in the parking lot," Sisk said. "We are all just ecstatic. We have been waiting for this for so long."