Well personally I don't find anything the family says very reliable. That's just my opinion of course.
Even if they did somehow "lose" the tapes would they really admit that to the family?
Everything nowadays is on computers. It's not like they have to go searching through a storage room for a tape.
More than likely, SCPD simply didn't pull the recorded file or discuss it with the family until they had a pow-wow with the brass.