Mary and Bob became convinced Kimball had killed Jennifer himself. Shortly afterwards, Mary secretly recorded this phone call with Kimball. Mary refers to Kimball as "Joe" in the call since he was introduced to her as "Joe Snitch."
Kimball told Mary he'd show her how her daughter was killed if Mary would allow him to bind her and have sex with her.
In this phone, call Kimball tells Mary that "she had her chance" to find out what happened to Jennifer, but ruined it when she refused to allow him into her motel room.
He also offers to demonstrate what happened to Jennifer on an escort.