International concern is growing over the fate of a woman arrested for removing her hijab in Iran at the end of last month.

The woman, whose name has still not been confirmed but is believed to be a 31-year-old mother, was arrested December 27 by Iranian authorities after a video of her waving a white hijab on the streets of Tehran went viral.

The video was shared by activists trying to raise awareness about the compulsory veiling of women in Iran using a slogan “White Wednesdays.”

Her image quickly became the face of the recent widespread protests in Iran that began the following day, December 28.

Though her exact identity has yet to be confirmed, rumors are circulating about all aspects of her life, including her 19-month-old daughter.

The woman was released shortly after her arrest only to be taken into custody days later and no information on her whereabouts has been available since.

Supporters are calling for her disappearance to be investigated while rights groups are calling for her unconditional release.

In the aftermath of her arrest, campaigners have taken her plight online using a hashtag #Where_Is_She in hopes of raising international awareness. Many Instagram and Telegram channels are also referring to her as #TheBraveGirl and #EnghelabStreetGirl, referring to the street where she took off her hijab.

At Saturday’s Women’s March in Boston, supporters held up signs bearing the hashtag and an image of the woman waving her white hijab.

Leading human rights organization Amnesty International has called for the immediate and unconditional release of the woman it said was taking part in a “peaceful protest against compulsory veiling,” and renewed calls to the end the practice of forced veiling deemed “abusive, discriminatory and humiliating” to women.

The group also says a second woman, 18, was also arrested on the same day and is currently being held at the Gharchak prison in Varamin near Tehran, where conditions have been described as very poor. The prison typically houses women convicted of serious criminal offenses.

Widespread demonstrations erupted across Iran in December with protestors initially angered by Iranian economic policies but quickly moving to express outrage against the theocratic regime in Iran and its policies of funding terror groups abroad over the plight of its own citizens.

Thousands of protesters were arrested and several perished while in detention; deaths the Iranian regime labelled “suicides” but were widely questioned.

Compulsory headscarves have been required in Iran since the 1979 Islamic revolution, with punishments of fines, lashings and even imprisonment for women who do not cover their hair.

Ironically, in December of last year, Tehran’s police chief announced that women would no longer face arrest for not wearing the hijab.