Authorities in Egypt detained an award-winning human rights lawyer on Sunday after she attended judicial investigations into protesters arrested during rare demonstrations against President Abdel Fattah al-Sisi. Mahienour el-Massry was arrested as soon as she left the state security prosecutor's headquarters in the capital, Cairo, where she acted as the lawyer for several people detained during the demonstrations, her lawyer Tarek al-Awadi said. Hundreds of Egyptians took to the streets in Cairo and several other cities across the country on Friday to call for Sisi's departure.According to the Egyptian Centre for Economic and Social Rights, 365 people have since been arrested.El-Massry, a political activist and human rights defender, has been tried and jailed twice for taking part in protests.In December 2013, following the army's overthrow of president Mohamed Morsi following mass protests, she was arrested and imprisoned until September 2014 on charges of participating in a demonstration without a permit.While in prison, el-Massry received the Ludovic Trarieux Award, an international prize given annually to a lawyer for contributions to human rights. In 2015, el-Massry was handed a year-long sentence for taking part in a sit-in during Morsi's rule. Also Sunday, Egyptian prosecutors ordered the brother of a prominent Egyptian activist to remain in custody for 15 days.