At a hearing in Washington, Beryl Howell, the chief judge of the US District Court for the District of Columbia, ordered the partial unsealing of an order on Hashemi, referred to by her former name of Melanie Franklin.
Once she finishes testifying before a grand jury that's investigating violations of a USA criminal law, the government expects that she'll be released, the order said.
Iran has called for the immediate release of TV anchor and documentary film maker Marziyeh Hashemian, whose employer, the English-language channel Press TV, said was arrested on Sunday by the Federal Bureau of Investigation (FBI) at St. Louis Lambert International Airport.
Marzieh Hashemi has appeared twice before a United States district judge in Washington, DC and has been appointed an attorney. She was then transported to Washington and has remained behind bars since then.
Hashemi-who according to news reports has USA and Iranian dual citizenship-was arrested on January 13 in St. Louis, Missouri, and transferred to an Federal Bureau of Investigation detention center in Washington, D.C., according to an article from Press TV. Tehran also condemned the "inhuman treatment of her in jail".
The FBI has not commented on the case. Asked whether his mother had been involved in any criminal activity or knew anyone who might be implicated in a crime, Hashemi said, "We don't have any information along those lines". She has worked for Iranian state television for 25 years, according to a report by the Associated Press.
"We want more clear answers", Hossein Hashemi said in a separate interview with Press TV.
Hashemi has been detained as a material witness, though it's unclear for which case.
Iranian government officials have called for her release.
In the years after the 9/11 attacks, the USA government was accused of abusing the "material witness" statute to detain people without charges or due process.
Hossein said he, his brother and his sister were also subpoenaed to appear before the grand jury.
The developments come after the Iranian government demanded the immediate release of Hashemi, adding that she was an Iranian citizen due to her marriage to an Iranian man.
Her detention comes amid heightened tensions between Iran and the USA after President Donald Trump withdrew America from the nuclear deal. The group's statement noted that 'Iran routinely jails journalists'.