An American journalist for Iran’s Press TV was freed in Washington by federal law enforcement officials on Wednesday, her son said, ending a detention that began on Jan. 13 when the F.B.I. took her into custody as a material witness.

The arrest of the journalist, Marzieh Hashemi, 59, had become a flash point of tension between Iran and the United States for more than a week.

Ms. Hashemi had been ordered to appear before a grand jury in Washington but was not charged with a crime. Her family and Iranian leaders accused American officials of disrespecting her Muslim faith while she was under arrest, forcing her to remove her hijab, or head scarf, and offering her only non-halal food.

The F.B.I. has declined to talk about Ms. Hashemi or the grand jury case in which she had been required to testify.