I have an idea of how Faith and Lily died.
Do you guys know scary things to read in the dark? There's a story called red ribbon. It's a little story about a girl who wears a ribbon and when she takes it off, she's head comes off of her body. Maybe that's what happened to Faith and Lily. They both weared ribbon because they worked at the strip club. When TJ told us about someone who was yelling at somebody on the bridge he/she maybe took the ribbon off of her head and her head fell off of her body.
But I have one other theory too. Maybe both of them broke the "These lips are sealed" rule. And it's some kind of a spell. When you break the rule your ribbon will open and then your head will get cut off of your body. Or maybe something else happens when you brake the rule. But both of the dead girls worked in the strip club and (as far as I know) all the strippers/hookers has that spell on them.