An Indian-origin man was Friday sentenced to four years in prison here after he pleaded guilty to sexually abusing a mentally challenged girl last year.
Shreya Lal, 21, of Lombard near here has also been ordered to register as a "lifetime convicted sex offender" upon his release from prison.
He was charged with sexually abusing a 20-year-old girl, who has the mental capacity of a 5-year-old, in June last year.
Lal's attorney John Donahue told DuPage County Judge Daniel Guerin that Lal was mentally ill and health experts have determined he suffers from "cognitive reasoning dysfunction".
Under the plea agreement that Lal has entered into for pleading guilty, he would receive treatment at a correctional centre for neurological, developmental and cognitive problems that stretch back to infancy.
He must serve 85 per cent of his sentence before being eligible for parole.
According to the complaint against him, Lal sexually assaulted his victim on June 15, 2009 at his residence after convincing her to come home.
He took his victim's cell phone from her and threatened her with physical harm if she reported the incident to the police.
Lal has remained in custody since his arrest in June last year.
Lal's victim lives with her mother, who had obtained a 2009 protective order on behalf of her daughter against Lal.
Despite the protective order, Lal admitted sexually assaulting the young woman, whom he had met on social networking site Facebook. He said she was his girlfriend.
He also admitted that he knew she was mentally disabled and did not having any understanding or ability to give consent to sex. The identity of the girl has not been released.
Lal has a history of indecent public behaviour. In 2008, Lal was placed under court supervision after he was convicted of public indecency, while exposing himself.
He also was investigated, but not charged, with offering to pay another mentally challenged girl USD 5,000 to perform a sex act in October 2008.
Born in India, Lal came to the US in 1999 and is now an American citizen.