In my mind, if you are working in a official government role and you knowingly destroy evidence of a potential crime, you are already guilty. It doesn't matter if there was actually a crime that was concealed by doing that, the public has a right to transparency and to have a thorough investigation conducted to determine if there was a crime, and you wrongfully deprived them of that.

It doesn't matter if there is some law requiring you to destroy that evidence, because there are also laws requiring that you not destroy evidence of crimes.