when 21-year-old ricky cowles and his teenage girl friend amy priestmeyer moved in together, her best friends moved in, too. at first it was like an endless sleepover, but then ricky was murdered. the killer bragged about the crime and police made a quick arrest, case closed. not exactly. unraveling who was behind the diabolical plot wouldn't be nearly as easy. here's keith morrison with "mean girls." "mean girls." >> an interesting species, teenage girls. some are sweet. some are not. some are not. we call them mean girls and some in particular, as you're about to see, could be very mean indeed. it was 1997 when their story began here in the high desert north of l.a., lancaster, california. there was sarah chapin, then 18, a cheerleader and local beauty queen. you were a pretty popular kid in high school. >> i wasn't really popular, about the i was a cheerleader. >> which helps. >> yes. >> amy priestmeyer 16, sporty, an a.p. student who looked like a girl next-door. >> amy and i were just two goofballs and we had a lot of fun. yeah, we partied, but things didn't get as serious until

cowling from arizona in the fourth round. he's the second receiver taken in this draft class. remember they took rickyt round. five of the niners eight picks were made today. they also selected a safety a running back offensive lineman and a linebacker. the challenge for the niners are you picking players for this season or the future? you know, being close like we were last year, feeling we're going to have a chance to at least have an opportunity to try to do something like that again. you want to think always what helps us now, but then you get to that spot and there always isn't that answer right then. and so do you. go with what kind of helps us now or what helps us more in the future. and so you're just constantly weighing that, whether it's the draft, whether that's free agency, it's a really good roster. so it's going to be tough to crack for these guys. we do believe that they have the skill sets, the mentalities, the makeup that they can come in and you know, they can come in and compete right away. and i think all these guys can contribute this year. all right. rookie minicamp is the second