Shahram Amiri, a university researcher working for Iran's Atomic Energy Organization, went missing during a pilgrimage to Saudi Arabia a year ago and Tehran accused Riyadh of handing him over to the United States, which Saudi Arabia has denied.
"The documents about Shahram Amiri's abduction by the CIA have been delivered to the Swiss embassy as the preservers of America's interests," Ramin Mehmanparast said, according Iran's official news agency IRNA.
It is the second time Iran has handed documents on the case to the Swiss who represent US interests in Tehran where Washington has no diplomatic mission.
"The serious demand of Shahram Amiri's family, along with public opinion in Iran, is to hand our countryman over to the embrace of his family and the Iranian society as soon as possible," Mehmanparast said.
In March, ABC news said Amiri had defected to the United States and was helping the CIA. The US spy agency declined to comment at the time but Washington officials have denied he was abducted by US agents.
Over the last month, conflicting video evidence has appeared on the Internet, showing a man claiming to be Amiri.
In the first video to emerge, broadcast on Iranian TV, a man says he was abducted and was being held in the United States.
He says he was forced to take part in a media interview "to claim that I was an important figure in Iran's nuclear program and that I had sought asylum in America of my own free will."
In a second video, a man also purporting to be Amiri says he was actually studying in the United States.
In a third video, which emerged at the end of June, the man says he has fled from US agents and is in hiding. He rejects the second Internet footage as a "a sheer lie" and urges human rights groups to help him return to Iran.
The man in all the videos looks similar to photographs of Amiri that have appeared previously in Iranian media, although none of them could be independently verified by Reuters.
Tehran initially refused to acknowledge Amiri's involvement in Iran's disputed nuclear program, which Washington and its allies suspect is being used to develop nuclear weapons. Iran says it is aimed at generating electricity.
Washington secured a fourth round of United Nations sanctions against Iran in June. Earlier on Saturday, Iranian President Mahmoud Ahmadinejad called the latest round of sanctions against it "pathetic."
Iran says it has numerous citizens in secret detention in the United States including a former deputy defense minister who disappeared in 2007.
Iranian media often link the case of three US citizens, arrested near the Iraqi border a year ago where they say they were hiking and held on suspicion of spying, to the fate of alleged Iranian detainees in the United States.
Some Iranian politicians have called on the United States to propose a prisoner swap.
