[origin_path]

You don't but this is a classic problem to do with proving guilt vs innocence, isn't it. You have to look for explicit evidence of tampering, instead of trying to prove a negative. That is, start from the assumption that the various actors began in a well meaning place, and then react to evidence of wrongdoing, rather than assume wrongdoing from the start and then try to prove innocence. Otherwise you can never bottom out.