If the player kills for an unid'd body, then it's likely that the console will show him IDing both bodies, but that is not always the case. You can use this information to confirm that the player was in the right for killing the other player for passing an unid'd body.
There's more serious things that should be added before this. For example, which weapon they had out. ID'd bodies is a minor thing. I can normally correlate the console info with the logs.