i'm your host, payne lindsay. >> my first goal was to find out what happened to tara grinstead. my second goal was to find out who had nothing to do with this. >> reporter: he worked alongside local reporter dusty vasey to gather whatever new clues they could. now this week investigators reveal a shocking discovery. >> a few days ago, an individual came forward and reported that they had information in tara's disappearance. >> reporter: a tip leading to the arrest of this man, seen here in his first court appearance yesterday. 33-year-old ryan alexander duke was a student at the school at which tara taught. graduating about three years before she disappeared. he had no prior criminal record, but now he's been charged with murder and concealing her death. he's also been charged with aggravated assault and burglary. duke has not yet entered a plea. >> they're going to interview him. if he doesn't talk, they really are sort of stuck with pulling his background apart and trying to figure out what are his movements? because clearly, for 12 years, he's been able to hide this crime. >>