A groundskeeper found Dubis on the Water Mill property on Aug. 8 and called police. He told police he was her husband, and then later, her adopted brother, the source said.
He was arraigned the following day on charges of burglary, criminal contempt, stalking and possession of burglar tools. He's being held on $100,000 bail and is awaiting a psychiatric evaluation. He's due in court on Aug. 28.
The singer's publicist said Lopez and her family were not at the house, and declined further comment.
Lopez bought the 3-acre Water Mill mansion in May.