daron wyatt was a patrol officer back then, and one afternoon his shift brought him to this park justhy had grown up. daron was about to bust a drug suspect when the guy started talking. >> he's playing the game of, you know, "i'll tell you whatever you want to know, just you know, ask the right questions and i'll tell you and then you won't take me to jail." so, you know, just almost as a flippant remark, i tell him, "okay, so tell me who killed cathy torrez." >> reporter: it was a shot in the dark. a tactic he'd picked up at a seminar for cultivating informants. >> and the patrol officer that is next to me starts kind of kicking my foot. and he's got an explorer scout who's riding with him -- a young hispanic female. and i look at her name tag and it was "d. torrez." turned out it was debbie torrez, cathy's youngest sister. >> reporter: who just heard you ask that question. >> correct. >> reporter: you had no idea it was her? >> i had no idea. >> reporter: debbie torrez -- cathy's baby sister -- was now 14 years old. eager, her mom says, to assist police because of everything her fa