Boston December 11, 2018 7:06 am Man Killed in Deadly Mattapan Shooting Boston police are investigating what they call the city’s 54th murder of the year in Mattapan. US & World Videos 2:27 Mother speaks out after school shooting threat in Milton 0:39 Police respond to incident in Whitinsville 2:31 Billerica police sergeant killed in crash honored at funeral 2:05 MIT monitors pair of opposing protests on campus 3:41 Cool air to linger over Boston into the weekend