what really happened to tara grinstead?liked high school teacher. >> reporter: tara also competed in beauty pageants, later mentoring other young women. that's what she was doing on the morning of october 22nd, 2005, the day she disappeared, recalls her best friend maria woods harbor. >> after the pageant, she went to a cookout, went home and nobody has seen her since. >> reporter: for years the case remained a mystery, but this man, john mccullough, says back in 2007 he tried to share with authorities information that he believed could have solved the case. a buddy he met in the army, above dukes, told him he knew who had killed tara. >> he had told me that his friend accidentally strangled her and he needed help getting rid of the body. >> so you called the police department. >> this is john mccullough. i know who killed tara grinstead. >> does anyone call you back? >> no. >> reporter: but a decade later, this woman, brooke sheridan, came forward with a similar story also from bo dukes, her boyfriend. she said ryan duke h