Treat Williams (Everwood, Chicago Fire) will appear in the finale of CSI: Crime Scene Investigation’s fourteenth season. (Spoilers after the jump!)
According to TV Line, Williams will play Sam, a former Sheriff’s Deputy who “demonstrated a knack for invention and an aptitude for forensic science” back in the late 1980s. He was a pioneer in the field, and he joins the CSIs when a cold case resurfaces involving the death of a 12-year-old. The CSI finale is scheduled to air May 7.