Gil Grissom is the head of the Las Vegas Criminalistics Bureau. An investigator of the old school, with seventeen years on the job, Grissom eschews computer simulations and readouts for hands-on technique and legwork. CSI is his life. He supervises a team of very diverse professionals, and often goes to the wall to protect them from department interference - and sometimes, from the consequences of their own risky decisions, on and off the job.
William Petersen has a distinguished background in film, theater, and television. His television credits include the films Long Gone, The Rat Pack, The Kennedys of Massachusetts, which won a Golden Globe Award, and The Beast. He also serves as executive producer of CSI: Crime Scene Investigation and was nominated in 2003 for a Golden Globe Award for his portrayal of lead investigator Gil Grissom.
His feature film credits include To Live and Die in L.A., Manhunter, Cousins, Young Guns II, Fear, Hard... More Promises, which he also produced, and The Contender.
Peterson made his Broadway debut in a revival of Tennessee Williams' The Night of The Iguana. In 1979 he founded the 'Remains Theater Ensemble' in Chicago with a group of fellow actors. He has appeared in a number of regional stage productions including A Streetcar Named Desire, The Time of Your Life, Glengarry Glen Ross, Fool for Love, and Speed-the-Plow.
Petersen was born in Evanston, Illinois, and first discovered acting while on a football scholarship at Idaho State University.