BEIRUT, Lebanon — For the nearly four years Nizar Zakka was held prisoner in Iran, an ordeal that lasted until he was released this week, the knowledge that he was little more than a political pawn made a bad situation almost unbearable.
“It’s just trading of human beings — they just trade us,” Mr. Zakka, a Lebanese citizen who had lived in the United States for much of his life, and who arrived in Beirut from Tehran on Tuesday, said in an interview after his release. “Every evening, you feel like you want to leave this life. You are an innocent person. You never hurt anything.”
Mr. Zakka, an information technology professional, was held for about three years and nine months after being seized without warning in September 2015 on his way out of Iran, where he had been officially invited to attend a conference. Accused of being an American spy, he was sentenced to 10 years in prison and ordered to pay a fine of $4.2 million. Despite the apparent gravity of the charges, however, the Iranian authorities agreed a few weeks ago to turn him over to Lebanese officials, who had been formally asking Tehran for his freedom for months.
The timing — in the middle of a period of inflamed tensions between the United States and Iran that have led to fears of war — caused some to question whether Mr. Zakka was, once again, the object of geopolitical maneuvering. Though Iranian and Lebanese officials said his release was simply a matter of diplomacy and good relations between their two countries during the holy month of Ramadan, Mr. Zakka said he interpreted his freedom as a conciliatory signal from Iran toward the United States.
But, he cautioned, it appeared to him and the advocates working on his behalf that Lebanon had initiated the move, and he emphasized that he knew of no talks between the United States and Iran concerning his imprisonment.
Iran’s semiofficial Fars news agency credited Hassan Nasrallah, the leader of Hezbollah, the Iran-allied Lebanese military and political group, with securing his release, while Lebanon said that President Michel Aoun of Lebanon, and Gebran Bassil, the foreign minister, had reached out to Iran. The head of Lebanese internal security, Abbas Ibrahim, who went to Tehran to collect Mr. Zakka, also acknowledged that Mr. Nasrallah had played a role.
“It was a good move by the Iranians, because they will look like they’re doing a favor for Lebanon as a friendly country, without giving concessions to the U.S.,” Mr. Zakka said. “The Iranians are using it to benefit by de-escalating the tensions.”
Iran still holds at least four American prisoners, including Michael R. White, a Navy veteran imprisoned since last July; Siamak and Baquer Namazi, an Iranian-American father and son; and Xiyue Wang, a Chinese-American graduate student at Princeton University who was arrested in 2016 on suspicion of spying while doing historical research for his dissertation. (Another American, Robert Levinson, a former F.B.I. agent, has been missing in the country since 2007.)
Mr. Zakka said he had been held for the last two years alongside Mr. Wang, in a cell he said they shared with dozens of other prisoners. It was so crowded that the space each man had to himself amounted to a narrow rectangle “little bigger than a coffin,” he said, where the two of them spent as many as 20 hours a day lying down, with short breaks for food or fresh air.
“You will never see anyplace so horrible, and Xiyue is left behind,” Mr. Zakka said, describing Mr. Wang’s condition as mentally sharp and strong, but physically “tired.”
Before he left, Mr. Zakka said, Mr. Wang asked him to promise him to help him get out, and gave him a letter to be delivered to someone on the outside. (He declined to identify the recipient, saying it might jeopardize Mr. Wang’s safety.)
“I told him that I will not leave him behind. I promised him that I will not rest until he’s freed,” he said. “He’s a student, he was doing his research. Nothing justifies him being left behind.”
Mr. Wang’s wife, Hua Qu, who lives in Princeton with their young son and has become an outspoken advocate for her husband, did not immediately respond to requests for comment.
Mr. Zakka said the two men were allowed writing material, and Mr. Wang was eventually allowed access to some books. They had 15 minutes a day to talk on the phone. Medical care was available, but slow to reach them. Guards had interrogated each of them at first, he said, but later left them alone.
As their hopes for freedom flagged, he said, their innocence both weighed on and fortified them.
“All the hostages should go home,” he said. “They haven’t done anything. They haven’t done anything.”