Particularly if your friend used XTOL, it's possible he ran into developer failure. XTOL has a reputation for failing unexpectedly, quickly, and without warning. This explanation is most likely if your friend mixed the developer several days or weeks before using it, and especially if it was stored poorly (in half-full bottles, say). FWIW, XTOL's packaging specifies room-temperature mixing, although some people prefer mixing it at slightly higher temperatures.
FWIW, I do tend to concur that this sounds like fixing before developing. A simple test to see if the developer will blacken a snip of film (a leader, say) might help clear things up. If the developer's bad, for any reason, this won't work. This can be done in ordinary room light, and the film snip need not be fixed; just develop it and toss it.