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William Louis Petersen (born February 21, 1953) is an American actor and producer, best known for playing Dr. Gilbert "Gil" Grissom on the hit CBS series CSI: Crime Scene Investigation. He portrayed President John F. Kennedy in the 1998 TV film The Rat Pack. Petersen was born in Evanston, Illinois, the youngest of six children of June (née Hoene; 1909–2006) and Arthur Edward Petersen, Sr. (1907–2004), who worked in the furniture business. He is of Danish and German descent. He has two brothers, Arthur, Jr. and Robert, plus three sisters: Anne, Mary Kay, and Elizabeth. He graduated... MORE

William Louis Petersen (born February 21, 1953) is an American actor and producer, best known for playing Dr. Gilbert "Gil" Grissom on the hit CBS series CSI: Crime Scene Investigation. He portrayed President John F. Kennedy in the 1998 TV film The Rat Pack. Petersen was born in Evanston, Illinois, the youngest of six children of June (née Hoene; 1909–2006) and Arthur Edward Petersen, Sr. (1907–2004), who worked in the furniture business. He is of Danish and German descent. He has two brothers, Arthur, Jr. and Robert, plus three sisters: Anne, Mary Kay, and Elizabeth. He graduated from Bishop Kelly High School in Boise, Idaho, in 1972. He was accepted to Idaho State University on a football scholarship. While at Idaho State, Petersen took an acting course which changed the direction of his life. He left school along with his wife, Joanne, in 1974 and followed a drama professor to the Basque country where he studied as a Shakespearean actor. Petersen was interested in Basque culture and he studied the Basque language, Euskara, and gave his daughter the Basque name Maite Nerea (meaning My Beloved); she was born in Arrasate - Mondragón 1975. Petersen returned to Idaho intent on being LESS