There are currently six crew aboard the space station:
- German Alexander Gerst of the European Space Agency
- Americans Drew Feustel, Ricky Arnold and Serena Auñón-Chancellor of NASA
- Russians Oleg Artemyev and Sergey Prokopyev of Roscosmos
I'm betting it's the German. An by "floated" I assume you mean "spaced?" I'm all for some sc-fi style justice. Out the airlock!
Realistically it was probably Ricky Arnold, just trying to hang a picture of his family and didn't realize the walls were so thin. Dammit Ricky!