Jeremy implies to Caitlin that he killed Nolan to "protect" her, though he never explicitly states it, leading the group to track him to the gala.
Sasha Pieterse (Alison), Janel Parrish (Mona), Sofia Carson (Ava), Sydney Park (Caitlin), and Eli Brown (Dylan). [S1E9] Lie Together, Die Together
The group attempts to use a recording of Dana confessing to manufacturing evidence to get her fired. However, Claire Hotchkiss is impressed by Dana's ruthlessness and keeps her on. Jeremy implies to Caitlin that he killed Nolan