It’s true, Gil Grissom is returning to “CSI.”

William Petersen has already filmed his cameo appearance in an upcoming episode of the long-running forensic drama, reports EW.com.

CBS hasn’t officially announced the date of Grissom’s highly-anticipated return — the character left the series in January 2009 — but it’s speculated that it might happen on Thursday, during an episode that involves his wife, Sara Sidle (Jorja Fox), his mother (Phyllis Frelich) and Grissom’s ex-girlfriend, played by returning guest star Marlee Matlin.