She was put on trial on charges of having sold her soul to the Devil, of carrying the Blessed Sacrament outside the church, having carnal knowledge with men and speaking blasphemously of the Pope.
This event became the subject of legend and the nun in question was split in two: one executed for fornication, and the other one for heresy.
The Systrastapi (Sister's rock) is where one of the nuns of the Abbey was buried after being burned at the stake.
During the Icelandic Reformation, Kirkjubæjar Abbey was declared dissolved and the property of the king and banned from accepting new novices, but the former nuns were allowed to remain in the building if they wished.
The former nuns are last mentioned in 1544, when six of them, Guðríður, Oddný (sister of the reformation bishop Gissur Einarsson) Arnleif, Ástríður, Margrét and Valgerður were still in residence in the abbey buildings with their abbess Halldóra Sigvaldadóttir.