Maraj was convicted of endangering the welfare of a child and predatory sexual assault on a child younger than 13, Nassau County District Attorney spokesman Brendan Brosh told People Magazine.
The charges against Maraj carry a maximum sentence of 25 years of life imprisonment. He will be sentenced on December 14.
The girl, now 14, had testified in the court against Maraj and detailed about her repeated sexual assaults that she said occurred when Maraj was alone in his house with her.
Maraj's lawyers had argued in the court that the accusations against him were fabricated in order to get his sister pay USD 25 millions to the girl and her mother.