>> the dna showed it belonged to dylan staalman. >> reporter: who is dylan staalman. police learned that he lived three blocks from the crime scene. and then chavez noticed a striking resemblance to the drawing that kristene had drawn. some quick computer searches reveal ed stallman had a criminl past. dylan stallman had just been convicted of an armed robbery in nevada. >> yeah. >> reporter: that nevada armed robbery occurred in 2010, a year and a half before the shootings. stallman and some accomplices broke into a home in a las vegas suburb and held a family hostage before robbing them and taking off. anybody get killed? >> no. >> reporter: and at the time of the shootings in 2012, dylan stallman was in the corpus christi area, awaiting sentencing for the nevada armed robbery. >> he'd been sent here to stay with a friend. >> reporter: what intrigued chavez was some unusual similarities between the nevada crime and the shooting in texas. >> we started going through the case file we started to see more and more things that are lining up. >> for example? >> the use of