William Petersen has played FBI and Secret Service agents and two generations of Kennedys, but it’s for his role as a forensic entomologist on the TV series “CSI” that most people know him.
Petersen’s career began when, on a whim and while on a football scholarship at Idaho State University, he decided to take an acting class. Shortly thereafter, the 21-year-old dropped out of school and moved with his wife, Joanne Brady, to Basque country in Spain so he could study as a Shakespearean actor. (In fact, Petersen was so entralled by Basque culture that he would give his daughter the Basque name for “My Beloved.”)
Petersen returned to Illinois, where he worked as a theater actor. After his divorce in 1981, he got his first bit part in the film “Thief” as a bartender. It wasn't until 1986 that Petersen began to book more regular screen work. That year, he played an FBI agent in “Manhunter,” the first Hannibal Lecter film. He famously struggled to shake the character when filming wrapped, and he even shaved off his beard and dyed his hair so that he wouldn't have to see the character’s face in the mirror.
In 1990, Petersen played John F. Kennedy's father, Joseph P. Kennedy, in the TV miniseries “The Kennedys of Massachusetts.” Eight years later, he played JFK in the 1986 TV movie “The Rat Pack.”
In 2000, Petersen was cast in the role of Dr. Gil Grissom on CBS' smash hit “CSI: Crime Scene Investigation.” He has appeared in more than 190 “CSI” episodes and voiced Grissom in four video games. He also played Grissom in a crossover episode of CBS' “Without a Trace.” But in 2008, Petersen announced that he would not renew his contract for “CSI.” He left the series after the 10th episode of Season 9 to pursue his love of stage acting, but he has returned for guest spots.