Actually that's more then likely. I mean what Mafia would throw their Mafia Cop out on the chopping block when they could throw a less useful Goon? Well unless there's only one mafia and their low on members now and their only remaining roles are other power roles.
Though with the frequent mafia deaths, I'm thinking there's either 1 big mafia, or 2 mafias. Too many mafia have died too fast for me to think it's just a standard 4-5 mafia set up. Unless our night killer is just that damn good. But the first 2 scenarios are far more likely.