Cook County detectives are looking for Michael Gargiulo in California, and connect with L.A.P.D. homicide detective Tom Small to help locate him. Armed with a search warrant, detectives track him to an apartment listed under his girlfriend's name, and arrest him. They submit his DNA for testing and get a match with the DNA collected from Tricia Pacaccio's fingernail clippings. When the Cook County State's Attorney's office is presented with the evidence, they decide not to charge Gargiulo due to the possibility of the DNA being obtained by "casual contact". We speak with DNA expert Kristen Mittelman and former L.A. County prosecutor Joshua Ritter on the decision by Cook County's State's Attorney not to prosecute Gargiulo. Plus, Tom Small tells us how the Pacaccio family reacted to the news.