After nearly six weeks in hiding at Moscow's Sheremetyevo airport, Edward Snowden walked calmly out of the transit area, ducked into a car and was driven away unnoticed.

It was an anti-climactic end to one chapter of a saga watched by the world in which the American, wanted in Washington for leaking details of secret U.S. surveillance programmes, stayed out of sight for almost 40 days and nights.

Hardly any pictures of him appeared in that time. One showed the 30-year-old meeting human rights activists at the airport, another showed him about to leave the airport.

But by the time that photograph was shown on Russian state television on Thursday evening, Snowden was long gone.

Many questions remain about the former U.S. spy agency contractor's time in the transit area, a no-man's-land for those with connecting flights who normally stay, at most, a few hours.

But a picture is emerging of a man who had become physically and mentally exhausted, increasingly anxious for some certainty about his future and desperate for something resembling normality after two months on the run.

"During his time there it was very difficult, psychologically difficult, because when someone's waiting he doesn't understand what will happen," his Russian lawyer, Anatoly Kucherena, told Reuters in an interview.

"His first desire was to gulp the fresh Moscow air."

Snowden was at first incredulous when Kucherena told him Russia had granted him a year's temporary asylum, and then delighted. Kucherena said he left the airport with a backpack, a string bag and a sense of relief.

"Imagine yourself daily (having to listen to) 'Dear passengers, the flight to New York, the flight to Washington, the flight from Rome'," Kucherena said.

"He needs a period of rehabilitation, or adaptation, because he is very tired and morally exhausted."

DISAPPEARING ACT

Snowden's trail went cold as soon as he landed at Sheremetyevo on a flight from Hong Kong, where he had feared he would be arrested after lying low there for two weeks.

Snowden did not come through the usual exit into the transit zone. Other passengers saw cars waiting on the runway and said he must have been whisked away by security officers.

"There were a lot of police and black cars when we were getting off the plane," said one passenger.

Snowden disappeared into the warren of corridors, rooms, and security zones that make up the transit area between the runway and passport control. – Reuters