voted "no". Dexter is a very convincing liar. Im sure he could tell Deb a half-truth about Travis kidnapping Harrison, Dexter chasing him etc, then killing him.
Voted "No", but this lack of jump implies Deb is going turn a blind eye to Dex and be fine with him killing, or he's going to keep her in the dark about what's really going on as far as multiple kills. We know Dex is going to kill some Russian guy - well, maybe someone else but Dex is mostlikely. So, I think an interesting question is, "How is Dex's next kill going to happen?", since it all depends on Deb's reaction.