The image of the young woman was posted on social media a day before the protests began.
A woman who became the face of protests in Iran last December is the subject of a new social media campaign in the country.
Images of the woman, whose name remains unknown, defiantly taking off and waving her white headscarf - a punishable offence - in central Tehran were shared thousands of times during anti-establishment protests at the end of last year.
Now, Iranians are asking: Where is she?
On Monday, earlier reports that the female protester was arrested on 27 December were confirmed to BBC Persian by human rights lawyer Nasrin Sotoudeh, who added the protester is 31 years old and mother to a 20-month-old child.