In addition, it requires that issues of ethical or legal transgressions be handled by "the proper authority". So absent a ruling by CPS (the proper authority in this case?), BA might actually have its hands tied. In this case, a suspicion of possible problems would have to be documented carefully so as not to damage this person's reputation through negligence.
If a BA FO is dressing as a Captain then why did BA not investigate or was it out of sight ? out of mind ?