When retributionist is controlled by a witch the body that they use is not consumed but still fulfils its function.
In a game I have played recently I controlled a bodyguard to protect myself and was witched. The bodyguard protected me as a mafia member attacking me was killed. The next night I noticed I could still use the same bodyguard and once again was witched but protected myself with a bodyguard (only one bodyguard died in the game so it was not a different person). The next night I still could use the bodyguard but wasn't witched or attacked. After that I could no longer use the bodyguard and was killed normally.