Baltimore ? A man who had argued with his estranged wife over the custody of their three children has confessed to drowning them in a hotel bathtub on the night they were to go back with their mother, police said Monday.

Mark A. Castillo, 41, of Rockville, was charged with first-degree murder and child abuse after his release from a hospital where he was treated for self-inflicted cuts to his neck, police said.

Police did not cite a motive.

But his wife wrote in court documents that her husband had threatened to make her suffer by killing the children. She sought a protective order Dec. 25, 2006, and asked that the court order Castillo to receive counseling.

“He has never actually hurt (the children), but did tell me that the worst thing he could do to me would be to kill the children and not me so I could live without them,” she wrote in the petition.

Police said Castillo called the hotel front desk Sunday afternoon, saying he’d killed the children and was going to commit suicide. Baltimore police and firefighters were sent to their 10th-floor room and discovered the bodies.