Well he isn't too good.

He shoots center mass. That isn't a snipre shot. Center mass is a hunter or grunt soldier shot. Can be fatal, but not allways. He hasn't killed all his victems, so I think he is not a pro.

However he understands one shot then leave. That IS a sniper tactic. Sniper never waits to confirm his kill. He allways has a spoter. This guy has the news for his spoter.

I do not think he is using a silencer no. Silencers can throw accruacy off. He started taking all shell casings not leaving a trace. Now he leaves them.

As far as I knw he only left the one note on the tarrot card. However if I was the police I would not dissclose all to the press.