An Indian-origin man was on Thursday 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 five-year-old, in June last year.