Kenzo can initially be found south of Aleroth's Great Market district (see map below) during the events of Divinity II: Flames of Vengeance. When you first encounter Kenzo, he is about to be executed by two guards that accuse him of treason. Speaking with the guards and Kenzo reveals that he had some letters addressed to the Black Ring, which he says he found.
Mindreading him costs 15000 exp but you find out that he really is a traitor. Selecting the new option that appears in your dialogue with him (something about "jeopardy") will unmask him and he will kill the guards and get away.
After he has run away, either by being accused with or without being mindread, he can be found again, talking to the guard Nerus at the entrance to Crow's Nest (after the courtyard in which Nericon the tree resides in Mardaneus Plaza). He will then promptly be executed due to having outlived his usefulness.