WASHINGTON — After more than three decades in existence, the Justice Department’s Nazi-hunting team is facing what could end up being its last investigation after reports emerged Tuesday that a 94-year-old Ukrainian immigrant in Minnesota had led a Nazi SS unit accused of burning villages during World War II. In northeast Minneapolis, news crews and curious neighbors milled outside the modest home of Michael Karkoc, who has lived in the United States for more than 60 years, after a report linked him to a Ukrainian SS squad. The Associated Press reported that wartime documents and interviews with soldiers indicated that...