I was listening to episode #25 of the Hello Internet podcast where Brady Haran mentioned that it's not unheard of for airline employees to rush to their own airplane's respective accident scene to deface the logos and registration numbers painted on the airplane's wings and fuselage. This is apparently done to reduce the damage to the airline's reputation. Below is an picture of the same from an alleged account of Thai Airways defacing the logo on a crashed (but still very intact) airplane.
So is there any law regarding whether this can be done? Could defacing the logo end up hampering the air crash investigation?