MADISON, Wis. (AP) -- The fourth and final person charged in an attack on former Badgers running back Montee Ball is in custody.
Twenty-eight-year-old Karlis Griffin was arrested on a warrant in Chicago last week. Griffin is in the Dane County Jail.
A criminal complaint says Griffin stomped on Ball's head during last summer's attack as Ball was walking home with three friends in Madison at bar time. Ball suffered a concussion and says he doesn't remember the attack.
The State Journal says Griffin has a prior felony battery conviction in Wisconsin.
Ball was taken in the second round of the National Football League draft by the Denver Broncos.