detective aaron veuleman had been working the case, and now he took the lead. >> what we first wanted expand the scope of the crime scene search because there was one crucial piece of evidence we didn't have at that point, which was a murder weapon. >> he hoped the murder weapon might definitively link spellman to the shootings. >> what'd that turn up? >> we didn't find anything, nothing of value. >> so you're back to kind of nowhere. >> that's right. >> and then? >> we received a phone call from the investigators at the sinton police department. >> those investigators in the neighboring town of sinton had just been given a letter addressed to kristene chapa's father. >> what does the letter say? >> the letter is written from the perspective of a hit man who has been hired to kill the surviving victim in this case, kristene chapa. >> in the letter, the hit man even named the person who had hired him. if you're wondering, the letter does not mention dylan spellman. all of it was a twist as big as texas. >>> coming up -- the mysterious letter. could this be the smoking gun police had be