The boy told jurors that Maraj allegedly slapped him several times across the face after the incident and told him he would never see his mother again if he repeated what he had witnessed.
Maraj, who had denied the allegations, was tried in Nassau County, New York. He faces 25 years to life in prison for what DNA evidence has supported happened to the now 14-year-old girl.
The Long Island newspaper Newsday reports that jurors convicted Maraj, 38, in Nassau County Court on Thursday, November 9, on a felony charge of predatory sexual assault on a child and endangering the welfare of a child. He faces 25 years to life behind bars, but his lawyer says they intend to file an appeal.
Neither Maraj nor his sister testified at the trial.
On December 1, 2015, Maraj was arrested on charges of predatory assault, second-degree course of sexual conduct and a misdemeanor charge of acting in a manner likely to injure a child. He is now being held at the Nassau County Jail until his upcoming sentencing.
His attorney, David Schwartz, did not immediately return a message from PEOPLE.
"We hope that today's verdict will help the family in the healing process and that it will close this awful chapter in their lives", District Attorney Madeline Singas said.
As Radar has reported, Maraj was accused of raping the child repeatedly while her mother was at work. She testified that Maraj referred to her as a "puppet" and physically assaulted her if she rejected his advances.
Maraj's ex-wife and the mother the victim testified that her daughter oddly became "distant", but made no objections when she married Maraj in August 2015.
Maraj maintains the rape accusations were invented by the victim's mother in an attempt to go after Nicki Minaj's family fortune. And Jelani Maraj did not testify in his own defense. Maraj, the boy said, told him to stay silent or he would be taken from his mother, says Brosh.