The two men have met almost weekly since 2012, sometimes in a government office, but also in New Jersey diners and Manhattan bars, including a Gilded Age tavern replete with marble and mahogany, and a watering hole that once served as a gathering place for fashion models.

Like the two bars, the men are a bit of a mismatched pair. Though both are in their early 50s and from New Jersey, one is a brash police officer with the Port Authority of New York and New Jersey, a 27-year veteran who heads the union that represents his 1,300 colleagues. The other is David Wildstein, the longtime political figure whose role in the George Washington Bridge access lane closings ended his career as a behind-the-scenes operative and as Gov. Chris Christie’s feared enforcer at the Port Authority.

Now their close relationship, described in interviews with a half dozen people who know them, has come under scrutiny as investigators piece together the events that led up to the lane closings and seek to untangle their roles in what has become a sprawling political morass.

Federal prosecutors recently questioned the union president, Paul Nunziato, as part of their inquiry into whether any aspect of the September lane closings amounted to a crime, according to people with knowledge of the session.