The American-born Iran state TV broadcaster said to be held by the FBI reportedly appeared in court Friday in Washington, D.C.

The appearance by Marzieh Hashemi, comes as the FBI continues to remain silent about her situation, including why she's being detained.

The newscaster, who also holds Iranian citizenship, was detained Sunday in St. Louis on a material witness warrant, her son has told The Associated Press. But the exact reasons for her detainment remain unclear and it has not been confirmed by authorities.

USDC Washington Chief Judge Beryl Howell ordered the partial unsealing of information pertaining to the case on Friday. Hashemi has not been accused of any crime and the U.S. government anticipates her release immediately after the completion of her testimony before a grand jury that is investigating violations of U.S. law.

Press TV, in a segment that aired on their channel Friday, reported that Hashemi’s children also have been called in to testify.

“Marzieh was very outspoken as far as the plight of Palestinians is concerned,” said Gisoo Ahmadi, a Press TV news anchor. “She was not shy to discuss the behavior of the U.S. government towards its people.”

Hashemi’s reported detention comes as Iran is continuing to hold several Americans in custody, some who have been languishing in prisons for years.

Fox News' Jake Gibson and Elizabeth Zwirz contributed to this report.