Killing is tier 1 as far as I know.
There is a killing move in tier 2.
Since you said you are tier 2 and Hayumi being a player who is hard to read then why not use Legilimens instead which is a cop ability?
Because I wanted to test kills, mainly because I wanted to see how prevalent kills failing will be (for instance, if there are hidden mechanics with wands etc). I didn't give it all that much thought, I just saw my ranking, saw the option was open to me, and figured eh, may as well fire a shot given I have nothing else to work from. So I just went over the list, and shot a player I figured I'd never read well.
The other reason I don't trust investigations all that much is because I assume there is a degree of manipulation present, otherwise the whole game would be busted open very quickly. It's partly why I was so loose with killing - I half expected it to fail or for more to fail given a bunch of people killing at once would also bust the game open. Really nothing else to my choice. I can see why you don't like the idea of killing so liberally, but eh, I don't think my decision was all that unreasonable.