>> in his confession, mr. styles said he saw another woman on the stairs and thought maybe that was crystie. that was you. >> uh-huh. and he said he considered killing me. >> that was devastating. >> you were that close to getting killed. >> getting killed. uh-huh. yeah. >> the detectives still had to figure out how to use c-styles' off the record con investigation to make an on-the-record case against derek. in the meantime, sisters michelle and monica couldn't resist going back to prowling the streets, looking for clues. cagney and lacey shift their focus to derek? >> we never thought he should get away with it. >> when the police said, "come in. we want to talk to you, we're going to reopen the case," i have a notebook now. i'm like, "oh smyers." so i wrote it down, and then i go back and i found, like, businesses they had. >> they also figured out where derek lived. you're regularly driving by his