He did nothing to defraud the bank or mislead it. He simply had access to a large line of credit, and used it. If the bank wants it's money back, that's a civil matter, not a criminal one. It's their responsibility to ask for it back.
This reeks of incompetence on the part of the bank, followed by outright malice. They put an innocent guy in jail in order to pretend that it was his fault that they screwed up.