Do they look at your bank account when doing your taxes? I mean, I don't think they do for us normal people (TurboTax surely doesn't)...but maybe it is different for people with insane assets and foreign citizen.
Even if he has someone else who looked at his account or saw it for whatever financial reason, there is one very important quality the person must have to see something like this: They actually have to care. As someone with a job that can occasionally come across and deal with levels of fraud, if the person looking doesn't care, nothing will be found. There was one case where a business owner owed money to 'employees'. In simplistic terms the business owner wrote the checks and then proceeded to sign them right back over to himself forging the signatures. Then the entire stack of checks went to bank together to get cashed into his account. Any bank employee with a sliver of care would have saw not only a bunch of checks with the same handwriting/ink, but also the fact it made no sense for two dozen people to all sign over checks to him over and over again.