(JTA) — The United States has asked Iran to free a Jewish U.S. citizen who has been detained there for six years.

In a statement issued Wednesday, U.S. Secretary of State John Kerry asked Iran’s new president  Hasan Rouhani “to work cooperatively with us”  to free  Robert Levinson,  as well as  dual-citizens Amir Hekmati, and Saeed Abedini “to return to their families after lengthy detentions.”

The request was made “respectfully,” as opposed to previous requests to former president Mahmoud Ahmadinejad which were much stronger, according to the Associated Press.

“These men belong at home with those who love them and miss them,” the statement said.

Robert Levinson, a private detective and former FBI agent from Coral Springs, Fla., disappeared from Kish Island, Iran in March 2007 while apparently researching a case. He is the father of seven children.

“His family has endured with courage and quiet dignity the pain of spending so many important family milestones without him there. They shouldn’t have to endure additional worry about his whereabouts and well being. We call again on the Government of the Islamic Republic of Iran to uphold its offer to help find Mr. Levinson and return him safely to his family,” the statement said.

Amir Hekmati was arrested two years ago on false charges of espionage; Abedini has spent a year in prison in Iran, part of an eight-year prison sentence on charges related to his religious believes, according to the AP.