Pittman's attorneys had argued that the popular anti-depressant Zoloft was to blame.
Members of his family insist he should have been acquitted and vow to fight to free him.
His sister Danielle Pittman told The Early Show co-anchor Harry Smith Wednesday she thought the verdict was "completely ludicrous. My brother is definitely not guilty, and I'm going to make sure that everybody knows that.
"There's nothing for us to be ashamed of. There's nothing for us to hide, and I'm going to get the word out there for my brother. He's locked in prison right now with a decision that was made that was completely incorrect, and he can't speak for himself. So I'm going to speak for him.
"If there was one person in the world that loved my grandparents more than I did, it was my brother. If there's one person that needed them more than I did, it was my brother. They were our stability, and why would someone go out and decide all of a sudden that someone who's never had background problems, that's never been in trouble, that's been shy, quiet -- why would you all of a sudden decide, 'Oh, I'm gonna got out and kill the people that I love the most.' It doesn't make sense."
She continued, "He is not at all the type of person the prosecution made him out to be. The prosecution made him out to be a cold, vicious, evil, cold-blooded murderer, and that's not what he is at all. He is the complete opposite. As I said, I'm going to fight for him and I'm not going to give up.
Pittman's grandmother, Delnora, couldn't agree more: "We got to talk to him shortly after the verdict, in the break room in the courthouse. There wasn't too much talking. More tears and hugs -- and definitely a promise that we will not let this stand. That we will never give up the fight. That in our hearts, we know he is innocent. They convicted a 15-year-old boy when indeed he was only 12 when this happened.
One of the jury members said the defense was grasping at straws, using Zoloft as a smokescreen. Pittman attorney Andy Vickery told Smith he takes strong exception to that: "It's astonishing to me. The prosecution's own expert, who is a consultant for Pfizer, who formally did clinical trials for Pfizer, testified that 'SSRI-induced mania' is a 'well-known clinical syndrome' and that somebody else, a 38-year-old police sergeant, should be excused of criminal culpability because of something that happened to him when he had the same reaction to a drug in the same class. So I was astonished that the jury felt that."
What about the jury only taking six hours to convict?
"It's astonishing that they did it so quickly. It's astonishing that, even the juror who spoke out, acknowledged that they thought the drug had an impact on him. When the law presumes that if you're under 14, you can't form criminal intent, and the jury finds that this is a mind-altering drug that had an impact on him -- how on earth can there not be reasonable doubt?"