The Long Island Serial Killer: A Mother’s Hunt for Justice tells the story of Mari Gilbert’s search for the truth behind what happened to her daughter Shannan, a sometime escort who disappeared after a ‘date’ on Long Island. After Shannan … Katharine Isabelle, Kim Delaney, Jason Gray-Stanford, Patrick Sabongui, John Cassini, Lucia Walters, Eugene A. Clark Added on HBO 2023-09-18.