She had black hair and was around fifteen or sixteen.
She escorted Min Farshaw to the Amyrlin Seat. Because Gawyn identified Min in front of Sahra, she was sent to the country as "penance" to keep her from gossiping about Min. While working on the farm, an Aes Sedai approached her and asked about Min. Sahra was killed after the interrogation.
The killer must have been of the Black Ajah since Sahra was interrogated and killed with saidar. The motive behind the murder was surely to find information on Min's connection to the Amyrlin Siuan Sanche; part of the plot to have her deposed.
Siuan receives a report that Sahra disappeared along with the farmer that managed the farm.