U.S. authorities investigated on Wednesday whether anyone helped an Afghan-born American citizen charged with carrying out bombings in New York and New Jersey, while the city's top federal public defender asked for access to the man.

Police in New York City also said they had not yet been cleared to speak to Ahmad Khan Rahami, 28, who was arrested on Monday after a gunfight with police in Linden, New Jersey. He has been charged with wounding 31 people in a Saturday night bombing in New York that investigators regard as terrorism.

The Federal Bureau of Investigation released a photo of two men who found a second, unexploded bomb they say Rahami left in a piece of luggage in Manhattan's Chelsea neighborhood on Saturday night.