19 Down (S09E09)

The discovery of a garbage bag containing a badly decomposed body leads CSIs to open up the case files of the infamous "Dick & Jane Killer", Nate Haskell. Eleven years ago Haskell went on a killing spree targeting at least seven young couples which he is now serving a life sentence. Unexpectedly, mito-DNA testing revealed hairs from the victim match Nate Haskell; sending the CSIs to theorize that Haskell had accomplices and our victim may have been one of them. Forensic evidence found in the victim's home, thought to be his killer's, is then linked to the murders of Ian Wallace and Justine Stephani; this is the unsolved murder of the couple we saw in episode #905 "Leave Out All The Rest". Grissom secretly joins the class of a well-known criminal pathologist Dr. Raymond Langston (Laurence Fishburne) who assists Grissom in getting Haskell to reveal the location of his first victim but simultaneously sends CSIs into a whole new realm of this case when a new male body is found murdered next to the remains of his first victim. The case in ongoing and will be picked up in a future episode. Equally shocking was Grissom's stunning announcement to the team that he will be leaving CSI. (CBS TV Network)