"Nelson's Sparrow" (Season 10, Episode 13) of Criminal Minds serves as a pivotal, emotional episode that deals with the off-screen murder of original BAU lead Jason Gideon. The team investigates his death while facing a 1978 cold case involving killer Donnie Mallick, a case that highlights the deep, long-standing bond between Gideon and David Rossi. For a detailed summary, visit Criminal Minds Wiki . Criminal Minds S 10 E 13 Nelsons Sparrow Recap - TV Tropes