LONDON — Call him the spy who wants to go home again. Except that Igor Sutyagin insists he is not a spy. And his friends warn him not to go home again.

“Everybody but one,” he said, “tells me run from that country.”

That country is Russia, where he was locked up for 11 years for working for a British consulting firm that Moscow called a C.I.A. front. Plucked from the bowels of a Russian prison camp, Mr. Sutyagin was freed last month in a dramatic spy swap arranged by the president of the United States even as America denied he had been a spy.

Mr. Sutyagin has had a decade to think about where he went awry, how sending foreigners information about the Russian military gleaned from newspapers could be taken for treason. But in the weeks since he and three other prisoners were traded for 10 Russian sleeper agents on a Vienna tarmac, he has struggled to come to grips with his abrupt liberation and his role at the center of a geopolitical bargain intended to preserve warming relations between the United States and Russia.

Deposited here in a strange land, Mr. Sutyagin was given a change of clothes and $3,000, then left to his own devices, a modern-day Rip Van Winkle emerging from the cold isolation of a remote prison near the Arctic to find a dizzying new world.

He has yet to see his family. He does not feel at home in London. In some ways, he said, he has simply traded one prison for another.

“I remember very well what Solzhenitsyn said,” said Mr. Sutyagin, the first of the released prisoners to speak with a Western news organization. “He said, ‘My biggest dream is to wake up someday as a free man in a free country.’ So that’s a reason for me to go back and find out whether I can wake up as a free man in a free country. Because without that, my liberation is incomplete.”

But so, he fears, is Russia’s, as society has grown more closed since he went away. “Over the last 11 years,” he said, “I had the feeling that the people who experienced the most complete freedom in Russia were the people behind bars. It’s very sad. You lose one peace for another. I don’t know whether it’s like that there, but I have to go back to find out.”

Slight of stature, his hair thinning on top, Mr. Sutyagin, 45, seems an unlikely figure in a drama that briefly captivated the world. While the other three men released by Russia were career intelligence officers, he was a scientist who never had security clearance.

Over the course of seven hours of interviews in London this week, Mr. Sutyagin adamantly denied any espionage. “No, of course I’m not a spy,” he said in a soft but firm voice. “Of course, I’m not a spy.”

He looked distraught as he described the pressure to sign a statement admitting otherwise last month when the Americans requested his release. “It’s a very simple deal: you give your honor in exchange for your freedom,” he said. “If it weren’t for my family, I would have stayed.”

The State Department said flatly that Mr. Sutyagin was not an American spy, an exoneration it did not provide the other three. Half a dozen government and intelligence officials from three administrations have said privately that they do not believe he was.

So why did the Americans ask for him? The White House called it a humanitarian gesture. He had long ago been declared a political prisoner by Amnesty International, and the United States has in the past traded spies for dissidents.

Mr. Sutyagin came of age as the Soviet Union collapsed and got to know Americans during the heady 1990s. As a visiting scholar at Stanford University, he met professors like Condoleezza Rice, who would go on to become President George W. Bush’s secretary of state, and Michael McFaul, now President Obama’s top Russia adviser.

As a young arms researcher at the Institute for U.S. and Canadian Studies in Moscow, Mr. Sutyagin attended a conference in Birmingham, England, and met representatives of Alternative Futures, a British firm advising investors in Russia. They put him on a contract for up to $1,000 a month, more than his day job. In exchange, he said, he provided analyses based on public sources like newspapers and government statements.

In October 1999, two months after Vladimir V. Putin, a former K.G.B. colonel, became president and began restoring the authority of the security services, Mr. Sutyagin was accused of treason. Although it took the F.S.B., the domestic successor to the K.G.B., five years and extraordinary legal contortions to make it stick, he remained in prison the entire time.

The first judge threw the case out because it was too vague. After the F.S.B. revived it, a second judge and jury were abruptly replaced midtrial. The third judge refused to let the new jury decide whether the information Mr. Sutyagin provided was actually secret; he was sentenced to 15 years.

In interviews, Mr. Sutyagin gave two examples of information he provided. One report he wrote on problems with Russia’s early warning system used information that had been published in The Washington Post. Another on the creation of new military units was based on public statements by Defense Ministry officials in Red Star, the official military newspaper. “It’s truly Kafka,” he said.

Was the mysterious British company a C.I.A. front even if he did not know it? That is where Mr. Sutyagin grew less certain. “I’m not a counterintelligence specialist so I can’t tell you,” he said. But, he added, “What kind of intelligence service is it that’s interested in information that six months ago was published in The Washington Post?”

Over the years, Mr. Sutyagin said the authorities acknowledged privately to him that the case was bogus. “Of course I realize,” he quoted an investigator telling him. “But if we admit that and let you go, we’ll take your place behind bars.”

His prison odyssey took him to four camps, eventually in the far north near Arkhangelsk. While behind bars, his daughters grew up — one is 18, the other 20 — and his father grew sick. On July 5, as he took a break from building a walkway, a prison official rushed up.

“Get your things together quickly,” he said. “You’re being sent away.”

He was taken to Lefortovo prison in Moscow, where the authorities catalogued his worldly possessions in typical Russian detail: 23 spare buttons, 17 paper clips, 106 postcards, 74 envelopes. Only when told to put on a shirt and tie for a photograph did he begin to suspect. Then he was taken to the prison director’s office, where three American officials and two Russian ones told him their presidents had agreed on his release.

He resisted. He did not want to sign a clemency request that included an admission, and he did not want to leave Russia. But he realized that forces were at work beyond his control. “I was between a rock and a hard place and if I didn’t sign, the rock and hard place would have pulverized me,” he said.

Mr. Sutyagin was put on a Russian plane with three other prisoners and flown to Vienna. As they disembarked, a Russian official gave instructions: do not say a word, do not look around, do not look at the other prisoners, do not make any gestures.

He was greeted by an American official he recognized from the Moscow embassy in the 1990s, a period when he was in frequent contact with foreigners. Once safely on the plane, another released prisoner asked for whiskey and there were toasts. When they landed in Britain, he and another prisoner were taken off, while the other two continued on to the United States, a decision he said he had no part in. The British put him up in a hotel at first. The Americans, he said, have not been in touch.

Today, Mr. Sutyagin is staying with friends of a friend. He talks by phone each day with his wife in Russia and wants her to visit London before he goes home. He has a valid Russian passport and a presidential pardon so there is no legal obstacle to his return — only the dire warnings of his friends.

He has written a book of 46 satirical prison stories he wants to publish. He relishes swimming in the sea, walking in the forest and eating watermelon. Skype has been a revelation. Strolling through the rain one day, he expressed amazement at London’s rent-a-bike stands.

His favorite discovery is Google Earth, which peers into secretive Russia like no spy ever could. Sitting at a computer, he used it to find his house outside Moscow. But he was uncertain whether it was the one on the left or the one on the right.

So instead, he brought up his prison camp. He had no problem identifying each building. “There’s no relief,” he sighed. “It’s becoming easier but it hasn’t ended for me.”