Catching people who prey on others for sex can be difficult, convicting them even harder. But three little letters, D.N.A. can lead to big results in tracking down a faceless suspect. Being able to identify a suspect this way, whether it's a sex predator case, or a murder case, is a huge help for law enforcement. In fact, D.N.A. evidence is being credited with cracking a 21-year-old rape and murder case in Kinston. Investigators say it's become a priceless tool in fighting crime in the 21st Century. That certainly applies to sex predator cases as well. Tuesday we continue our special focus on sex predators by taking a look at what parents can do to help keep their kids safe on the internet.