[PeterisP]

Sure, but removing all traces is hard and most criminals are careless, sloppy or dumb.

I mean, if this particular case is real, someone has performed a serious crime, risking years in jail, for a comparably trivial reason and small gain - it's not an indication that the perpetrator is likely to be risk-averse, meticulous and smart.

If we were looking at a forged email as a part of a sophisticated campaign for extracting secret information or defrauding very large amounts of money, then it would be likely that the forgery is done carefully by skilled people thoroughly removing all traces - but for a reason like this? not likely. Heck, digital "intelligence ops" by major governments sometimes leave traces due to some sloppiness or carelessness, it's very hard to be sufficiently thorough.