On August 18, 2008, it was reported that Laurence Fishburne would join the cast of "" after William Petersen, who played Gil Grissom, left the series. John Malkovich was also considered for the role prior to the announcement. Fishburne joined the show on the ninth episode of the 9th season as a college professor and former pathologist whose area of expertise involves some criminals' predisposition to commit acts of violence. The character was introduced as a consultant on a case ("19 Down"), who winds up joining the CSI team ("One to Go"). In May 2009, Fishburne performed on-stage in the National Memorial Day Concert on the Mall in Washington, D.C.