My guess is either sex, or a connection somehow to a dance/lap dance.Was the $20 dollar bill left as a meassage to Cheryl, here is payment for sex - basically calling her a call girl? Does that mean that she knew the killer and she had spurned his advances? Often times, men that are turned down when a girl likes someone else - they call the girl a “who**”
Cheryl had worked as a waitress at a strip joint previous to the murders. She wasn't working there at the time of the murders, but I believe there's a strip joint connection between her and the rape victim who was a dancer at a different strip joint.
I have nothing to base this on, but I believe the killer threw the 20 dollar bill at Cheryl before he killed her and not after.
All speculation.