An American-born news anchor for Iran's state-run television station was arrested Sunday by the FBI at St. Louis Lambert International Airport while boarding a flight to Denver, her oldest son Hossein Hashemi-Niasari said in a phone interview from Washington with NBCBLK.

The anchor, Marzieh Hashemi, who is black and Muslim, was transferred to Washington, where she is being detained.

On Wednesday, when she was allowed to contact her children, Hashemi told them that male authorities had forcibly removed her hijab. She said she is able to walk around a courtyard but with her feet shackled, and has only eaten pretzels while in detention because she has been offered only foods that conflict with her religious dietary restriction.

“I believe it was pork and other kinds of meat,” Hashemi-Niasari said. “They didn’t have vegetarian options. She won’t eat food that’s been in contact with meats that she doesn’t eat.”

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Hashemi, a Louisiana native, was born Melanie Franklin and is a convert to Islam. She was visiting the United States to film a documentary on the Black Lives Matter movement and to visit a brother who has cancer. When she was approached by authorities, she was given vague details on why she was being handcuffed, her son Reza, who was at the airport with her, told other family members. She said in her phone call to family that she still hadn’t been charged with a crime.

The FBI did not respond to a request for comment on why Hashemi was being detained.

News of the arrest came days after it was reported that a Navy veteran, Michael R. White, has been detained in Iran since July.

A spokesman for Iran's Foreign Ministry, Bahram Qasemi, condemned Hashemi's arrest as "highly political" and a "blatant violation of human rights," and called for her to be released immediately, according to the state-run Islamic Republic News Agency.

Hashemi’s family learned that “she’s being held as a material witness," according to Hossein Hashemi-Niasari, but the family is having difficulty proceeding with legal representation because of the vague nature of her detainment.

“Because we don’t know what it’s related to, we don’t know who the right specialists are,” Hashemi-Niasari said. “A lot of the lawyers we speak to don’t want to come on just yet because they don’t know if it’s along the lines of their work.”

According to her son, Hashemi has been an outspoken critic on international and domestic issues like the school-to-prison pipeline and regime change policies in other countries.

“It’s difficult not to feel conspiratorial about what is going on,” Hashemi-Niasari said. “She’s a very high-profile journalist in Iran and other places as well. It’s difficult to see how she could be a side note to some bigger case without any caution taken in her arrest.”