Spring Break Massacre (2008)
Years ago, a girl and two guys are hanging out. She's going to party later with her girlfriends so she tries to kick them out. One of them pulls out a knife and kills her. At around that time the pizza delivery guy walks in on the scene of the murder. The suspect is sentenced to jail.
In the present a cop and a fed discuss some crime at a crime scene, a girl is a survivor. And in long flashbacks we learn what happened. Some kids (some look actually pretty old to be college kids) hang out during spring break at a lake. The guys of course want to spend time with the girls. But the girls have other plans--a slumber party. It will take place at Heather's house. Her father left for a couple of days and a creepy neighbor offers to help if she needs anything. The guys in the meantime spend time at a bar and argue whether to visit the girls anyway.
It's not long before the creepy guy starts stalking the girls, the lights go out, and some of the guys end up killed. Some of the cops in the meantime vanish and someone helps the killer from the intro escape from jail. More killings ensue and we find out eventually who's behind all of it. (IMDB TdSmth5) V&D