When the Prosecutor uses their ability on someone, a "trial phase" (same as someone being voted up) begins and the pros + the defendant are the only ones that can talk (chat is disabled for everyone else, so no whispers).
During this time, the Prosecutor can choose to vote Guilty or Inno (buttons would appear the same way as during a public trial), and at the end of the phase, their fate will be up to the pros (if abstain, GUILTY will be chosen by default).
If the target is innoed - They cannot be voted up again for the day
If the target is guiltied - Existing game behaviour of Pros
Reasoning: There is already an existing period where the Pros/Target can talk, but it literally serves 0 purpose, since the target will be dead anyway. This makes that period longer, and actually makes it do something: Allow the target to defend themself. This will allow the Pros to back off if they realise they made a mistake, at no harm to the town (except consuming an ability charge)
BTOS 2: If innoed, it just takes up one of the 3 trials for the day. If guiltied, it ends the day as usual