Police hunt for the gunman who killed UnitedHealthcare's boss in Manhattan

Investigators are searching for clues that could help them identify the masked gunman who stalked and killed the leader of one of the largest U.S. health insurance companies on a Manhattan sidewalk, then disappeared into Central Park.

UnitedHealthcare CEO Brian Thompson, 50, died in a dawn ambush Wednesday as he walked to the company's annual investor conference at a Hilton in Midtown, blocks from tourist draws like Radio City Music Hall and the Museum of Modern Art.

The killing, and the shooter's movements in the minutes before and afterward, were captured on some of the multitudes of security cameras present in that part of the city.

One video showed him approach Thompson from behind, level his pistol and fire several shots, barely pausing to clear a brief gun jam while the dying health executive tumbled to the pavement.