A "person of interest" is being questioned in police in connection to the killing of healthcare insurance boss Brian Thompson last week in New York.

The individual was carrying a similar gun used in the shooting of the UnitedHealthCare CEO.

It is not confirmed if the person is the suspect.

The unidentified man also was found with a silencer and a fake New Jersey ID.

He was approached by officers after customers at a McDonald's restaurant flagged his 'suspicious' behaviour to the police.

Sources told NBC News that it is "too soon" to determine whether the man is connected to last week's murder, however, officers believe it could be a "potentially significant development".

The 50-year-old executive was gunned down in what police described as a "brazen, targeted attack" outside the New York Hilton Midtown on December 4.