When Bitsey saw the towel lying on the floor she remember seeing a similar towel lying on the floor scene from the murder tape. Then she remember seeing it moves a little. So she decides to recreate the murder scene and check it out.
The conversation between them was like this:
BITSEY : Did you throw the towel on the floor?
ZACK : What?
BITSEY : The towel on my bathroom floor. Did you put it there?
ZACK : Yeah, I guess. It's a hotel room. What --
BITSEY : Do you do that at home?
ZACK : No. Fuck, Bitsey. I'm sorry, it's not like it's --
When she find the towel lying on the floor as it was she thought of something, and she tries to recreate the crime scene. Uses the help of Nico and she lie down as shown in the tape.
And showing this scene in a TV near to another TV showing the murder tape. Now BITSEY and ZACK look at the two TV images, roughly the same. The murder tape, however, shows what looks like a white towel in the lower right-hand corner. Bitsey points to it.
Then they talk as :
BITSEY : What's this?
ZACK : Towel or something.
BITSEY : Okay, look at this.
She plays the tape of Constance for eight seconds.
BITSEY : I noticed this back at the hotel. See?
Bitsey touches the TV screen by one of Constance's feet.
The foot moves ever so slightly. She hits pause.
BITSEY : She moves her foot. Why?
ZACK : Fucking good question.
BITSEY : It's another fifteen seconds before she comes to. If she had passed out once, without fresh air she wouldn't come back. There was no head trauma, her blood tested normal --
ZACK : Jesus, maybe she was faking, hoping he would go away.
BITSEY : Or...
Bitsey want to confirm it so she wants to bag her. Then Bitsey puts the bag on her head, rips off a long length of tape. She seals the bag around her neck. She then handcuffs herself from behind, with some difficulty.
After that scene she realizes that it was done by the women herself.
BITSEY : She used the gloves to keep fingerprints off the tape and bag. Then she put them back on the dish rack, but upside down and inside out, a housewives' habit. A murderer would have just tossed them aside, like they were the first time we were here, like you do a towel in a hotel.