Complex sentence: The two discover the bodies of Stevie, Morgan, and Diane in the pool before beginning to believe that Slater is responsible for the attacks and travels to the graveyard where Vicki and Liz are attempting to bury the body.
Split into simpler sentences: The two discover the bodies of Stevie, Morgan, and Diane in the pool before beginning to believe that Slater is responsible for the attacks. Meanwhile, Vicki and Liz are attempting to bury the body.