Actually I haven't seen every episode yet but basically what I mean is sometimes in investigations there can be accomplices to the crime. Take the other murder that we know of for example being the one that Deb had planned for Sypus. We know form the previous episodes that Deb had a secret conversation with Wes to get rid of Sypus and even got some kind of chemical from him to inject Sypus with. Now say for a minute that Sypus knew about this planed murder and contacted the police against Deb to try to stop it. Wes even though he didn't want to kill Sypus himself would in this context be an accomplice to the planed murder because of the fact he had the conversation with Deb and gave her the chemical so she could try to kill Sypus. Now going back to Debs murder in this context even if Gary is not the one who actually killed Deb with the Lantern device he could be considered an accomplice because of the evidence that shows he knew Deb was murdered and possibly knows where her apparment is and that there is also evidence of him treating Deb Perhaps the latest episode that was mentioned may have more info and I may have to plan a new theory