First of all, it doesn't take hours to overwrite several text files and a few binaries. Second of all, I think I know better what my local cops would do. It's not NSA or Interpol. Lastly, this hypothetical obviously excludes stuff after which 'motivated investigation' might come. That kind of data lives in encrypted files tucked in odd places, and even that can probably be wiped from the directory entry like it was never there.