I earn a living (well, if you can call it that) doing biochemical research, but frankly I don't care if you believe me (RTFA, it pretty much speaks for itself).
Sorry, not bored enough to give examples, but using google scholar will most definitely help you (if you are that bored ;-).
Possible vector of contamination? Are you serious? Try just about everything they may have come into contact with.... removal of "all things resembling RNA" is much easier than it sounds... destruction of RNA strands, yes... quite easy (however that may introduce yet more contamination ;-). Removal of all nucleotides... good luck.
Contamination is actally quite a good shot as to what may have brought on at least the start of the process...
Did I mention I'm not that worried if you don't believe me? :-)