Maybe he didn't actually pull the trigger but he was definitely behind all four. He was by far the most dangerous Mafia composer and is responsible for starting the trend of hiding guns in violin cases
So I'm thinking MC, that's 1100 in Roman numerals therefore M is 1,000. I think if you meant master of ceremonies it wouldn't be capitalized and would more-likely be m.c.
I just now realized what it meant. I thought it wanted the first name of MC Hammer, and I had no idea - I was trying Michael, Maurice, Mason, etc. However I tried Martin which gave me another one I didn't know so I can't complain.
I would suggest changing the clue for Madonna to 'Singer who had two hits that began with 'Like a...'' which I saw on another quiz; it is a much more notable fact and makes it easier to get, as well as helping the quiz-taker learn something new.
The More You Know