The ministry seems to use the Dementor's Kiss as a last and ultimate punishment for its criminals, like Sirius Black and to a certain extent, Barty Crouch Jr (even if his death was unsanctioned). If this method of "execution" is used, then, what happens to the body of the victim? I always wondered what happened to Crouch after he was kissed.

It is stated that a person still exists without a soul, possibly in a coma like state. What does the ministry do with these living but "empty shells"? Are they kept in a ward at St Mungos? (In which case that would use up space and money) Or do they kill the body? If they did the latter, why bot kill them in the first place instead of taking away their soul?