Back in the day, being a lowly night shift computer operator(IBM 360) we reused tapes by writing over them on a fixed schedule. The only time we degaussed tapes is if we had an inordinate number of errors.
(and then had to ship them to the home office)
Me smells something mighty fishy
If they are not recoverable then that would be a destruction of evidence situation. But that felony won’t be prosecuted.