IT WAS still dark at 6.40am on December 4th when Brian Thompson walked alone from his hotel to the Hilton in Manhattan’s midtown. A resident of Minnesota and the chief executive of UnitedHealthcare, one of America’s biggest health insurers, Mr Thompson was in town for his company’s annual Investors Day. Just as he arrived at the Hilton, a masked gunman approached from behind and shot him several times. He was pronounced dead at a nearby hospital. Jessica Tisch, the city’s police commissioner, called the killing “a brazen, targeted attack” that “does not appear to be a random act of violence.”