A 40-year-old man, Choi, who raped his live-in girlfriend's 9-year-old daughter with a mental disability has been sentenced to prison. 

According to the court records, Choi started to live with his girlfriend, a 37-year-old who also has a disability. The girlfriend's 9-year-old daughter lived in a residential care institution, but in November of 2013, the girl visited her mom at home. During the visit, Choi beat and raped the 9-year-old when no one else was home.  

The victim told what happened to her aunt, who then reported the crime to the police. 

SEE ALSO: Arson suspect dies after setting fire to apartment building following noise complaints

However, Choi denied any wrongdoings because he believed that no one would believe the girl since she has a mental disability called, 'William's Syndrome.' Instead, Choi testified that the aunt was against his relationship with the victim's mother and was framing him in order to take him away from the 37-year-old girlfriend. 

The court did not buy Cho's argument. Even though the victim's IQ is only about 50 - 70, the court concluded that the girl's testimony was believable because of the specifics of her disability. Those with William's Syndrome have lower mobile and spatial abilities, but they have an excellent memory and learn trade skills quickly. 

The court stated, "Considering the victim's intellectual capacity, her testimony could only be from her real experience...She could not have made it up. We conclude that her testimony was not forced by her aunt." The court then sentenced Choi to 6 years in prison and 80 hours of rehabilitation. His information will also be available to the public.