William Louis Petersen is an American actor and producer, best known for playing Dr. Gilbert "Gil" Grissom on the hit CBS series CSI: Crime Scene Investigation, Richard Chance in the film To Live and Die in L.A., and Will Graham in the film Manhunter. Born in Evanston, Illinois, Petersen attended Idaho State University on a football scholarship, where he first tried acting and immediately joined the drama department, before leaving to work in the Basque country as a Shakespearean actor. Peterson embraced the Basque lifestyle, influencing his w…