They contacted and worked with a handful of doctors/surgeons specializing in amputations, which examined the bones and explained how an amputation that resulted

They contacted and worked with a handful of doctors/surgeons specializing in amputations, which examined the bones and explained how an amputation that resulted in the damage observed could have happened, and could not have happened - and they all independetly agreed that this had to be deliberate. At least that's the short summary I remember from one of the scientist on the bbc science podcast.