joshua cooke says he has the answer. he is known as the matrix murderer. >> i would see myself in that role. >> the teenager who picked up a shotgun and killed his parents in their suburban virginia home. now joshua cooke tells his story in an exclusive prison interview with piers. >> i don't blame anyone but myself. >> the crime, the confession and a warning about the next adam lanza. >> these people were ticking time bombs. >> this is a special "piers morgan live" inside the mind of a killer. >> good evening. it's been ten years since joshua cooke did the unthinkable. on february 17th, 2003, the then 19-year-old picked up a shotgun, pointed it straight at his mother and father, and pulled the trigger, killing them both. how could he murder his parents? why did he do it? for a decade, joshua cooke has kept the motive a mystery until now. for the first time, the killer dubbed the matrix murderer is speaking out about the crime that made headlines across america and put him behind bars for 40 years. this is more than one

name is joshua cook. >> a lot of these shooter games, when i would play these games, i just -- it did lot for me mentally where i could release my aggression with these games, and i could almost bring my fantasies to fruition the way i would just immerse myself in these games. sometimes i would play them 12 to 15 hours a day without leaving my room. >> i mean, it was pretty clear he felt there that this was a direct link. and my sense is if people are slightly disturbed to start with, these games can make them more disturbed and potentially trigger them doing something. i don't see how this, which is, you know, like an ar-15 shot in houston, looks a bit like it, fires like it, how is that not to a disturbed mind, and this is a sniper rifle. >> yes. >> how are these not going to make people like joshua cook, adam lanza and others, immediately i hate this. >> i agree with you. we had this discussion. >> i can see they're hugely popular but i hate them. >> yes. >> it is like a rifle, very exciting. a lot of kids will be doing this who potentially have a form of mental illness, we have se