The Bayonne man's identity is being withheld to protect the victims and was ordered detained through his prosecution following a detention hearing Monday, NJ.com reports.
One sister told authorities she was 12 when her mom's boyfriend forced her to perform sex acts with him in 2018, the complaint said.
The now-15-year-old girl said she and a third sister walked into the bedroom and found their mom's boyfriend under the covers with their 9-year-old sister.
The man molested one victim while her mom was out multiple times while she was between 6 and 9 years old, and told her that if she told her mom about it, he'd tell her she broke an iPad -- which would get her kicked out of the house, NJ.com says citing a criminal complaint.
The 9-year-old said she didn't come forward because she thought "everyone would get mad at her," the complaint says.
The sisters' grandmother later found out about the assaults and told the girls' mom, the complaint said.
The man was arrested Dec. 11 and charged with first-degree aggravated sexual assault, two counts sexual assault and three counts of endangerment.
Click here to follow Daily Voice Hudson and receive free news updates.