Doctor murdered; Gun legally obtained

A cardiologist was murdered yesterday at the Brigham and Women's Hospital in Boston by  the son of a former patient.According to the Boston Globe:

Millbury police Lieutenant Donald Desorcy said Pasceri was properly licensed to possess a firearm. “They are a very good family,” Desorcy said. “Never any problems, as far as we are concerned.”

So he was licensed "properly" according to our laws. The gun also worked "properly" as intended by its manufacturer and owner. If the shooter had been a member of "a well regulated Militia" defending the State, that would be one thing. But of course it's not the case.