John Pontolillo, an undergraduate student at Johns Hopkins University, killed an intruder who broke into his off-campus house with a samurai sword. Pontolillo's home had been broken into earlier that day, and when the student heard noise coming from his garage he grabbed his sword and went to investigate. The intruder lunged at him and with only one blow Pontolillo severely lacerated the intruder's chest and severed one of his hands. The intruder, Donald D. Rice, died of his wounds. Since the student appears to have been acting in self-defense, it is unlikely he will be charged with a crime, however that is for the state's attorney to decide.
You can read more about this case here.
Watch a video report of the incident below.