according to lead prosecutor, paul maggiano. >> that's when they were facing life without parole.operating became all the more relevant to them. >> that's when they admitted that they had killed greg smart, but there was more to it. billy said that pamela was involved. in fact, the teen said that she was the mastermind. >> what was his version of events to you? >> basically, pam had said to him that they can never be together unless craig was killed. >> police heard a story of seduction and manipulation. that billy had become spellbound by the sensuous, and more experienced, pamela smart. he would do anything for her, even kill. >> the original plan was for him to try and find someone to kill greg smart. they really couldn't find anybody to kill him, so eventually, pam started putting pressure on billy, like you have to kill him, and this is how you can do it. >> maggiano says billy tried and failed a few times to kill greg, and then asked his friends for help. >> for the life of me, i'm not sure why they agreed to help. they agreed to help in part because pam says to them, you ca