If he has committed a minor infraction or a misdemeanor then he is still entitled to vote. If he is in jail more than 1 year then it is a felony and he cannot vote.
Convicted felons cannot vote unless their voting rights are restored by the Governor. Those convicted of only misdemeanors or being held prior to trial are not disenfranchised. I would guess that those who retain their right to vote can only do so by absentee ballot while imprisoned.
Probably not, but it depends on the crime. If he committed a felony, he is no longer allowed to receive a lot of the privileges given to American citizens. He won't be able to vote in any election for the rest of his life--even after he is released from prison and deemed rehabilitated.
No, once you are a convicted prisoner you lose your right to vote in any elections. In fact you will not be able to ever vote again if you are convicted of a felony and server a sentence in jail. This should be considered before committing a crime. This is how we protect our government.
Well that depends on whether your brother had committed a folony. Yes, prisoners may vote as long as they are not felons and many prisons even take time to allow prisoners to vote.