UnitedHealthcare CEO shooting: New clues emerge as gunman hunt continues – National [Video]

As the investigation into a masked gunman who stalked and killed the head of one of the largest U.S. health insurers moved into its third day Friday, possible leads emerged about his travel before the shooting and a message scrawled on ammunition found at the crime scene.

UnitedHealthcare CEO Brian Thompson was killed in a dawn ambush Wednesday as he walked from his midtown hotel to the company’s annual investor conference across the street, blocks from tourist draws such as Radio City Music Hall and Rockefeller Center.

But days later, the gunman was still at large and the reason for the killing remained unknown, with New York City police saying evidence firmly points to it being a targeted attack.

Investigators worked to piece together more of the timeline of the gunman’s whereabouts before the shooting, examine security camera footage and even test a discarded water bottle and protein bar wrapper in a hunt for …