My opinion on this.

I believe one of them is telling the truth.

At the moment I'm leaning toward Slowpoke... Because according to the Mafia Wiki, the mafia may also be called Werewolves. If this is true then Kadabra's role would be ficticious. One problem, how do we know Del and Mirel didn't make their own rules and branch off?

We don't.

We have to Lynch one, because one of them is lying. At the moment I vote we lynch Kadabra. Because if we lynch him and he is mafia then we know that we have our cop, who he is, and we're Good. If we find out Mafia isn't scum, we know exactly who to lynch next.

Why trust Slowpoke right now? Cop is important, if he's telling the truth and we lynch him, we may as well have shot ourselves in the foot.