Capcom revealed the psychopath in Uranus Zone, the new amusement park area made for Dead Rising 2: Off the Record. Stilts the Clown has a grudge to settle with Frank West. His older brother, who also happens to be a clown, was killed in the Willamette Incident by Frank. I believe Stilts is referring to Adam the Clown, one of the psychopaths in the original Dead Rising.

Dead Rising 2: Off the Record comes out on October 11 in North America and October 14 in Europe.