'Happy Face' killer Keith Jesperson hints Rex Heuermann may have more victims in prison letters ahead of Gilgo Beach murderer's June 17 sentencing.
https://www.foxnews.com/us/happy-face-killer-warns-fellow-serial-killer-rex-heuermann-could-tossed-wolves-prison
https://www.foxnews.com/us/happy-face-killer-warns-fellow-serial-killer-rex-heuermann-could-tossed-wolves-prison