I like this concept, especially since it is a role related to the legal industry! Also, it puts people in a position to be weary of VFR practices.
However, I think it is a bit OP in its current state, but I have some constructive criticism, if taken, could keep the Prosecutor balanced yet still a Mafia powerhouse in the right hands!
Also, I put in some suggestions on renaming or rewording some things that I think would drive home the lawyer aesthetic, but I digress. Those are more ideas rather than criticisms.
1)
Role Summary. I think your summary could be a bit more concise and to the point. I would change it to something like this:
"A bought-off district attorney who always gets a guilty verdict."2)
Alignment. On technicality, the Prosecutor would be Mafia Support, not Deception, because it does not conceal or manipulate Town information. It falls more into the et cetera category for Mafia, hence Support.
3)
Charge Mechanics. A charge should act like everyone voted guilty, especially in regards to the Jester, meaning the Jester could haunt anyone still living. On that note, the Jester charge refund and subsequent immunity should be scrapped. The odds of charging a Jester and getting them on the chopping block are slim enough to be an achievement, so I think its fair game. Additionally, Mafia could use the Prosecutor's ability as leverage to make a deal with a Jester. Next, removing a revealed Mayor's immunity would be nice since rationally, the only time the Prosecutor would even think about trying to charge a Mayor is when they feel positive that Mafia/evils will win. The only person who could be immune is a Guardian Angel's target since a Guardian Angel prevents their target from being voted up. This should not be refunded. Lastly, I think the frame mechanic should be removed. That's the Framer's job.
4)
Consigliere Results Prosecutors are less of politicians (except DA's, AG's and the like, but even then, it's not the point since they aren't lawmakers), so I was thinking something like this:
"Your target abuses the justice system. They must be a Prosecutor!" Also, I find it hilarious, so... yeah, there's that.
5)
Role-Independent Achievement Names:
Tipping the Scales: Win 1 game as a Prosecutor.
County Attorney: Win 5 games as a Prosecutor.
District Attorney: Win 10 games as a Prosecutor.
Attorney General: Win 25 games as a Prosecutor.
6)
Role-Dependent Achievements:
Foolish Fools*: Get a charged Jester lynched.
Overruled!: Have your target be protected by a Guardian Angel.
Turnabout for the Worse*: Get automatically lynched due to being charged.
King of Prosecutors*: Successfully charge three targets in one game.
Injustice is Served: Successfully charge an Executioner's target.
(* I am a huge Ace Attorney fan, so it biases my name choices, but I hope you like the concepts at least!)
Again, I think this role has potential. I can tell you put in some time to think this out, and it shows. Good job!