A look at the seven Iranian prisoners released by the U.S.

The U.S pardoned or dropped the charges against seven Iranians in a prisoner swap for the release of four Americans held by Iran. The seven were accused or convicted of violating U.S. sanctions. Six of them have dual U.S.-Iranian citizenship, and it is unclear if these individuals will leave the U.S. for Iran.

The Justice Department released the following names and backgrounds on the seven:

Nader Modanlo

Modanlo, a naturalized U.S. citizen, was sentenced to eight years in prison for violating the trade embargo and helping Iran launch its first-ever satellite into orbit.

According to court documents, Modanlo was a mechanical engineer who received science and engineering degrees from George Washington University. Modanlo said in court he was an internationally recognized expert on strategic policy and finances affecting the space-based telecommunications industry, and that he managed space and science programs for private companies, the Department of Defense and NASA.

Bahram Mechanic

Mechanic, a dual citizen who lives in Houston, was indicted last year on charges he illegally exported millions of dollars in U.S. technology to Iran.

Mechanic, 69, is the co-owner of Iran-based Faratel Corporation and its Houston-based sister company Smart Power Systems. Faratel designs and builds uninterruptible power supplies for several Iranian government agencies, including the Iranian Ministry of Defense, the Atomic Energy Organization of Iran and the Iranian Centrifuge Technology Company, according to the charges.

The technology Mechanic sold to Iran is used in a wide range of military systems, including surface-air and cruise missiles. Between July 2010 and 2015, Mechanic's network allegedly obtained 28 million parts valued at about $24 million worth and shipped them to Iran through Taiwan and Turkey. Among the parts shipped were microelectronics and digital signal processors, according to the indictment.

Khosrow Afghahi

Afghahi co-owns Faratel Corporation in Iran and Houston-based Smart Power Systems with Mechanic, according to an indictment.

U.S. prosecutors say Afghahi, 72, of Los Angeles, helped Mechanic to illegally provide U.S. technology to Iran.

Tooraj Faridi

Faridi, 46, is vice president of a Smart Power Systems and along with Afghahi assisted Mechanic in the illegal transfer of U.S. technology to Iran, according to court documents.

Mechanic, assisted by Afghahi and Faridi, also of Houston, regularly received lists of commodities, including U.S.-origin microelectronics, sought by Faratel in Iran, according to an indictment.

Arash Ghahraman

Ghahraman, 46, was sentenced to more than six years in prison last year for violating the trade embargo after he participated in a scheme to purchase marine navigation equipment and military electronic equipment for illegal export to Iran.

Prosecutors argued in court the naturalized U.S. citizen, who lived in Staten Island, New York, acted as an agent of an Iranian procurement network and used a front company in Dubai to illegally acquire U.S. goods and technologies to be sent to Iran.

A maritime engineer, Ghahraman also worked at shipyards in the U.S.

Nima Golestaneh

Golestaneh, an Iranian national, pleaded guilty to hacking the computer system of Arrow Tech, a Vermont-based aerodynamics company and U.S. defense contractor, to steal software.

Golestaneh, 30, was arrested in Turkey in 2013 and extradited to the United States last year. He was the only Iranian released Saturday who doesn't have dual citizenship.

Ali Saboonchi

Saboonchi, 35, was convicted in 2014 of exporting industrial products to Iran though companies in China and the United Arab Emirates.

A U.S. citizen who was living in Parkville, Maryland at the time of his arrest, Saboonchi conspired with others to evade the Iran Trade Embargo and export to Iran numerous industrial parts, including hydraulic valves and connectors; and liquid pumps and valves, which can be used in the oil, gas, energy, aerospace and defense industries, authorities said.