The Two Mrs. Grissoms
CSI Season 11 Episode 13 (02/03/11)
A professor at a local college for the deaf was killed by a car bomb at a fundraiser that Sarah and Grissom's mother were attending. Sarah initially suspected Professor Julia Holden, a former girlfriend of Grissom's, of the crime. However, after Julia's office was bombed and she was injured suspicion shifted to other students at the college.
Julia's T.A., and another student of hers, Sean Wyatt who was also her lover, were the new suspects. The T.A. admitted to being angry with Julia and the other professor for not giving him a large grant. He suggested that Sean Wyatt was not all he appeared to be.
Indeed, it turned out that Sean wasn't even deaf, and was conning the school in order to get receive grant money. Sean and his cousin, an interpreter at the school, killed the professor because he discovered that Sean's transcripts were faked. The bomb in Julia's office was planted to shift the focus of the investigation.
Meanwhile, Sarah dealt with conflicts between herself and her mother-in-law concerning the fact that she and Grissom rarely saw each other.