She definitely killed someone.
The killer to Audrey in 2x1:
''Thought you could get away with murder, didn't you?''
Why would she be so scared to tell her friends that she was somehow involved with Piper unless she did something really bad? I mean she even knew that Jake was dead and didn't tell anyone or the police, because she knew that she would get into serious trouble if the police started investigating and/or the killer would tell the cops what she did.
Bringing Piper to Lakewood because of a documentary is not a crime.
Instead, she knew Piper was a murderer and she helped her.
(watch 2x03, she even wants to knock Noah out with the bookend when he tried to sync the camera.
)
