A professor at the Massachusetts Institute of Technology was fatally shot at his home near Boston, and authorities said Tuesday they had launched a homicide investigation. Nuno F.G. Loureiro, a 47-year-old physicist and fusion scientist, was shot Monday night at his home in Brookline, Massachusetts. He died at a local hospital on Tuesday, the Norfolk District Attorney's Office said in a statement. The prosecutor's office said no suspects had been taken into custody as of Tuesday afternoon, and that its investigation was ongoing.