Investigators probing the murder of UnitedHealthcare CEO Brian Thompson have discovered a backpack in Central Park believed to have been carried by the killer. Police yesterday conducted a huge sweep of the iconic urban park in Manhattan, New York City, scouring lakes, ponds and a densely wooded section called "The Ramble". It was part of their hunt for the killer of 50-year-old Mr Thompson, who died following an ambush at dawn on Wednesday as he walked from his hotel in the city to the company’