Editor's note: This story was updated after publication with new details. A 22-year-old St. Louis man was gunned down late Wednesday night aboard a MetroLink train pulling into the University of Missouri-St. Louis station — the second deadly shooting along the rail system in less than three weeks.
The victim, Jesse Boone of the West End neighborhood in north city, had been in a physical fight with another passenger as they rode in the back of the train, according to St. Louis County police.…