TEHRAN -- It’s a rare upbeat story to cover in Iran: the release of Iranian-American businessman Reza Taghavi from Tehran’s notorious Evin prison after two and a half years behind bars. The only reporters allowed into the country for the event, we were the first to greet the 71-year-old from Orange County, as he walked free. He gave us a rare account of conditions inside the prison. Taghavi described living with 33 fellow inmates in a cell with only 16 beds, and enduring repeated broken promises that he’d be released. To pass the time, he read books from the library and looked forward to Wednesdays, when episodes of '24' were screened in the prison amphitheater.

“I’m seventy-one yrs old, I don’t have time. Two-and-a-half years is a long time for a seventy-one year old man to be in jail,” he told us.

“Every day I was waiting for something to happen. Every day, waiting, waiting.”

His crime? Allegedly giving $200 to an anti-regime terrorist group called Tondar, which Iran blames for the 2008 bombing of a mosque in Shiraz in which 14 people were killed. Taghavi maintained—and the Iranian authorities told us they eventually agreed—that he thought he was giving a gift to someone in need in Tehran.

However, it quickly became clear that his release was not a humanitarian gesture. Since the moment he walked out of prison, Iranian officials have escorted Taghavi and us from photo-op to photo op with the victims of terror attacks that the government blames directly on the United States.

At the Shiraz mosque, victims of the bombing confronted Taghavi—and us.

“Why does the American government support terrorism here,” one woman asked me. “Will you tell the American people about the suffering your government is causing here?”

When I asked 32-year-old Ali Reza, who lost an arm in the bombing, if he believed the U.S. Government was behind the attack, he nodded with a smile. “Yes, I do,” he said. “Because the group operates freely in America.” Taghavi himself was made to apologize. “On my part I am really sorry for what happened to you,” he told the victims. “I hope some day we will see each other nice and well."

Iranian officials base their claim on the fact that Tondar maintains a media operation out of Los Angeles, presided over by an Iranian, Iman Alaf. It was he who gave Taghavi the $200 to carry into Tehran in 2008. Iranians often carry small amounts of cash to friends of friends. And Taghavi had no previous connection to the group. Mr. Alaf himself claimed that Taghavi acted unwittingly.

The Taghavis enlisted American lawyer and former Bush administration ambassador-at-large Pierre Prosper to help secure the Californian’s release. Rather than publicizing his case and working through the U.S. government, Prosper negotiated quietly and directly with Iranian officials, making three trips to Iran during 14 months of talks.

“We did our job by showing Mr, Taghavi was not associated with Tondar and was in fact a victim of this organization, and we believe that the government here accepted the information we have,” said Ambassador Prosper.

But as I pressed Iranian officials, it became clear that some were less than convinced of his innocence. And more broadly, they say Taghavi’s case proves the allegation of American sponsorship.

“I think they realize that with the release of Reza Taghavi, that it's an opportunity while the world is paying attention to get their point of view across and they're using every disposable means available,” Prosper added.

This week, I met with a senior Iranian counterterrorism official who told me that the United States backs most, if not all, terrorist groups in Iran.

And he claimed that he believes Taghavi intentionally aided Tondar. When I asked how a $200 gift from a multi-millionaire amounts to evidence of material support to terrorists, he said it only costs about $15 to build a bomb.

Iran routinely doles out prisoner releases to score propaganda points. Sarah Shourd was made to meet with victims of attacks by the MEK, an anti-regime group that the government blames for 16,000 deaths in Iran since the 1979 revolution. We were taken to meet with MEK victims ourselves on this trip. But it’s clear the government intends to trumpet the terrorism charge more loudly and boldly than in the past. And Iranian officials told me they expect Taghavi to press the point home on his return to the United States, by suing Tondar in court and meeting with U.S. law enforcement officials to share what he knows of Tondar’s terror activities. Until they’re satisfied, they told me, Mr. Taghavi’s case will remain open.

Jim Sciutto is a senior foreign correspondent for ABC News.