Whats the name of that one movie?

ummm i think its about some dude trainin this chick to kill because in one scene, some crazy guy (the guy that played harry potters godfather? sirius black) he went on a killin rampage (to the music of Beethoven i think) to some family in their apartment but he didnt kill a daughter b/c she was out grocery shoppin but when she came back--she coolly played it off by goin to a neighbor n praying for him to open the door.