Interesting... in a mission where the prisoner is supposed to be returned, I get a critical success and lost the prisoner (the assumption is he went back to prison). However, the caption next to the prisoner says "Prisoner did not survive the assignment."
Hmmmn, I guess it must have been one of those Section 31 missions where we look the other way for a moment....
I have to reccomend NOT doing this mission. Dominion Prisoner exchange has better rewards.
Namely, the fact that you get a DOFF.
"My frozen dairy-based confectionery attracts all the males of the species to the facilities. They all agree on it's superiority. Indeed, it is superior to yours. I could teach you the finer details but that would require monetary recompense on your part." -The Milkshake Song: Vulcan Edition