Possessing less than one ounce of marijuana is no longer a crime in Massachusetts.

But crime still flows from supplying it.

To understand how far and how violently, consider again the story of Justin D. Cosby, who was murdered inside a Harvard University residence hall — several months after the decriminalization law took effect. Cosby, 22, a Cambridge Rindge & Latin School graduate who attended Salem State College, sold marijuana on and around the Harvard campus. On May 18, 2009, he was set up by three men — not Harvard students — who were part of a plot to rob him. He was shot three times and died later at a hospital while his mother watched.

READ MORE: Pot not a crime, but trade still has victims
Boston Globe, April 28, 2011