Hashemi and his brother Jamshid Hashemi were persecuted by the Shah's SAVAK during the 1963 White Revolution, and left Iran as a result. The Hashemis had connections with Ahmed Madani, who was exiled in 1970 and went on to become Defense Minister after the 1979 Revolution.
The Hashemis supported the 1979 Iranian Revolution, and Jamshid was appointed to oversee the national radio network, where he worked with Mehdi Karroubi's brother Hassan. Hashemi said he was a cousin to Akbar Hashemi Rafsanjani, an aide of the Ayatollah Khomeini who was elected Speaker of the Iranian Parliament in 1980.
From November 1980 to January 1981 wiretaps were placed in the New York offices of the First Gulf Bank and Trust Company, of which Hashemi was the head. The bank had handled clandestine money transfers for the Iranian government, with Admiral Ahmad Madani, then the Defense Minister, ordering $30–$35m transferred to an account there in late 1979.
A 1992 Senate investigation concluded that Hashemi was involved in a 1980 CIA attempt to funnel $500,000 to the campaign of Iranian presidential candidate Ahmad Madani, ahead of the Iranian presidential election, 1980. Charles Cogan met with Hashemi and his brother Jamshid in New York on 5 January, and in the context of the Iran hostage crisis the Hashemis "promised to put U.S. officials in touch with top officials in the Tehran government, including a family member of the Ayatollah Ruhollah Khomeini", but asked for financial support for Madani. The CIA provided $500,000 in cash on 17 January, which was rejected in favour of a wire transfer via Switzerland. Hashemi later returned $290,000 to Cogan, via the office of John Stanley Pottinger, after Cogan had determined that less than $100,000 had been spent for its intended purpose. Madani later testified to the House October Surprise Task Force that he had told off Hashemi for attempting to collaborate with the Republicans behind Carter's back; he said Hashemi had offered to bring Casey to a meeting to discuss a hostage deal.
According to the Los Angeles Times, by the mid-1980s Hashemi, although maintaining an appearance of wealth (such as commuting to his London office in a gold-trimmed Rolls-Royce) was facing bankruptcy, in part due to major gambling losses sustained in London casinos.