No, but what if the wounds don't match a kabar? Or if they have a piece of the knife and it doesn't match a kabar? As I understand it, the Kabar sheath is only made for a kabar knife? JMO
If LE has a piece of the knife, they have a very good idea of what type it is and if someone owns a 7" Ka-Bar sheath and a 7 " Bowie sheath, there's a very strong chance they own two very aggressive knives because the sheaths are very well made and intended to last as long as the knife.