>>2179731 (lb)
Not unless they have the actual magnetic media in-hand. I suppose they could have everything if they caught everything as it was written. But if anything was written to the magnetic media and not caught live as it was written (rather picked up later from surveillance), then something wrote over that/those location(s) on the surface–that wouldn't have been caught. It would take special equipment used on the physical media to negate the level of magnetism at layer #1 without disturbing the magnetism at layer #2 so that layer #2 could be read through the zeroed-out layer #1.
Imaging software only pulls what's visible at layer #1… well, except for VERY special software one of our branches of military has.