BBC News
By Patricia Sulbarán Lovera
image captionLuisa wrote a letter to a member of Congress asking to be released
A mother and her daughter, both from El Salvador, have spent more than 500 days at an immigration detention centre in the US, despite a rule limiting the detention of under-age migrants to a maximum of 20 days.
Luisa has the sweet voice of a nine-year-old girl, but she sometimes sounds wise beyond her years. She has had to write letters to legislators, asking authorities to release her and Ariana , her mother, from a US government detention centre for migrant families.