52-year-old Raul Ochoa from California pleaded guilty of child rape and sex slave and will now serve 22 years behind bars.
Ochoa was arrested, charged and convicted of child rape after he held his mentally disabled relative as a sex slave for many years, prosecutors said.
The girl was subjected to repeated sexual and physical abuse between 1999 and 2012.
The 13 year old girl was first abused by Ochoa but in 2012 she finally managed to escape with the help of a relative.
Ochoa attempted to scare the victim and dissuade her from testifying against him to the police.
His mother also helped him to intimidate the girl.
Ochoa is now restrained from contacting the victim and three of her relatives.