Bones - Season 11, Episode 13: Soundtracks

Booth listens to the their victims cassette tape; Brennan listens to the sound byte while reexamining the case files; Christine climbs out of bed to confront the monster in her closet. 

Bones becomes preoccupied with reassembling, redressing and re-articulating Allison's skeleton. 

After figuring out what type of screws where used on the victims, Booth & Bones use the placement of the notches to figure out that the killer turned his victims into marionettes after he killed them.