The Washington Post’s Tehran correspondent , Jason Rezaian, and his wife, Yeganeh Salehi, were detained July 22 in Iran. (European Pressphoto Agency)

The State Department on Monday called for the release of The Washington Post’s Iran correspondent, Jason Rezaian, who was detained last week in Tehran along with his wife and two others for undetermined reasons.

Jen Psaki, a spokeswoman for the State Department, said Washington had asked the Swiss government, which helps with U.S. consular cases in Iran, for assistance in Rezaian’s case. The United States and Iran do not have formal diplomatic relations.

“We call on the Iranian government to immediately release Mr. Rezaian and the other three individuals,” Psaki said Monday afternoon during a State Department news briefing.

The Post’s executive editor, Martin Baron, said last week that the newspaper was “mystified” and “deeply concerned” about the arrest, which an Iranian judicial official confirmed Friday.

Rezaian, 38, who holds American and Iranian citizenship, has been The Post’s correspondent in Tehran since 2012. His wife, Yeganeh Salehi, 30, is a correspondent for the National newspaper, which is based in the United Arab Emirates.

Salehi’s parents, Fatemeh Talaeee and Koroush Salehi, issued a statement over the weekend expressing concern about the detentions.

“Yeganeh and Jason love Iran and have always tried to show a fair picture of the country in their reporting,” the couple said. “As their parents we have the right to know how they are after six days. We do not know why they are being held but we are certain they have done nothing wrong and would never do anything against Iran.”

Rezaian was born and raised in Marin County, in the San Francisco Bay area. He and his older brother Ali had relatively little exposure to their Iranian father’s homeland until Jason was in his 20s and their dad started going home for visits.

“Once my dad went back the first time, Jason became very interested in it,” Ali Rezaian said in a phone interview from San Francisco. “He started studying Farsi on his own.”

After completing his studies at the New School, a university in New York, in 2000, Jason Rezaian began spending long stretches in Iran, where he worked as a freelance journalist for Western news organizations and helped produce a documentary called “A World Between.”

At the time, there was some optimism that Iran was becoming more welcoming to dual nationals and the international community in general, Ali Rezaian said.

“It was really important to him that people understand what life was like in Iran,” he said.

Jason Rezaian’s roots in Iran deepened several years ago when he met Salehi, who is Iranian, through mutual friends in the journalism community. The two got married in April 2013 in Iran, in a wedding that blended Jason’s bi-national family and Salehi’s more traditional one.

“The wedding was beautiful,” Ali Rezaian said. “Everyone had a wonderful time; it was a wonderful ceremony.”

The pair have been particularly drawn to feature stories about issues that are not in the news but give readers a taste of modern Iran.

Salehi, for instance, recently filed a piece on the controversy ignited by an Iranian imitation of the hit American television series “Modern Family.” One of Rezaian’s most recent reports was about surging enthusiasm in Iran for baseball.

As one of the few American-born journalists in Iran, Rezaian was keenly aware of the rigorous rules and procedures foreign correspondents must follow to remain accredited as journalists in the country. He and his wife were mindful of the risks of reporting in a country where the news media is tightly controlled, his brother said.

“Jason is aware of the rules and what he was licensed to do,” he said. “They respected the process put in place there.”

In recent months, the couple planned to start spending significant periods of time in the United States, where Salehi has been approved for permanent residency. They were planning to travel Saturday, Ali Rezaian said. Instead of hosting a homecoming, relatives spent the weekend scrambling for news and leads about the case.

“At this point, the government hasn’t told us where they are being held or what they’re being questioned about,” the brother said.

Hamid Babaei, a spokesman for the Iranian mission at the United Nations, did not respond to an e-mail Monday. Officials have not provided information about the arrest of another couple detained that night, a female photojournalist and her husband. Relatives said Monday that contrary to earlier reports, the husband does not work as a journalist.

News of the arrests has brought back grim memories to Roxana Saberi, an American-Iranian journalist who was detained in 2009 while working in Tehran. Saberi, who works for Al Jazeera America in New York, recalls being interrogated while blindfolded during sessions that dragged on for days.

Detained journalists are often held in solitary confinement, coerced to make false confessions and urged to disclose sensitive information about colleagues and acquaintances, Saberi said in an interview Monday.

“The uncertainty is one of the scariest parts,” she said. “They can make you believe that you can stay there for 10, 20 years or even get the death penalty if you don’t cooperate.”

Saberi said Iranian officials urge detainees to tell their relatives not to publicize their plight. She said she’s glad her relatives and supporters didn’t abide by that request.

“I haven’t seen many cases where staying quiet has helped,” she said. “In high-profile cases like this, it seems the more of a public outcry there is, the better. I believe there are decision-makers in Iran that do care” about the international backlash.