If you know for a fact that innos who say they have killed a traitor when for example you have killed them, you can kos them.
They could have called them out or attacked them and not received the kill. Even if that weren't the case there are very few cases where you can be 100% certain and even then its still not kill-able.
If you never called them out beforehand or didnt assist in killing them and you say you did, its more than likely gonna things into me killing you. Not by itself but when combined with a couple things, its almost always a deal sealer.
