CSI: Crime Scene Investigation (season 13) Las Vegas ("In Vino Veritas"), Phillips heads to a high school reunion ("Dead of the Class"), and an investigation into a series of Dante's Inferno killings bring the CSIs face-to-face Black Sabbath ("Skin in the Game"), before jeopardizing the life of one investigator. In episode thirteen of the season, "CSI" staged a two-part crossover with its spin-off show "" in which Gary Sinise marked his first appearance in "CSI" and as his "CSI: NY" character Mac Taylor; cast member Ted Danson subsequently appeared in the "CSI: NY" portion of the story. Former cast member William Petersen also returned as Gil
CSI: Crime City discover that Monica was receiving unwanted attention from both the hotel waiter, Blake who also moonlights in the hotel spa and Pierre, another hotel guest who had shared drinks and made an unwanted play for Monica on the night of her murder. Upon further investigation CSI discover that Blake seemed to be following Monica around even swapping shifts with a colleague at the spa so that he could 'give it his best shot' with Monica and Pierre who had checked out of the hotel in a hurry leaving behind his expensive but smashed watch at the scene of the crime.