YOU SAID:
Mafia killed every night?
INTO JAPANESE
マフィアは毎晩殺した?
BACK INTO ENGLISH
Did the Mafia kill every night?
INTO JAPANESE
マフィアは毎晩殺しましたか?
BACK INTO ENGLISH
Did you kill the mafia every night?
INTO JAPANESE
毎晩マフィアを殺しましたか?
BACK INTO ENGLISH
Did you kill the mafia every night?
That didn't even make that much sense in English.