NYPD divers had been searching the Bronx River since Monday. The father,  Arius Willaims, was caught on surveillance video throwing a bag, possibly with the child inside, into the river, sources said.

The boy’s father told his mom over the weekend that he had thrown their son into the Bronx River. He also told his mother, Sabrina Williams, the boy was still alive.

“He good. He good. Don’t worry about it,” the dad told his mom over the weekend.

The 17-year-old mom had not seen her son since May 10. Two days later, she went to family court to report that her son was missing, but a warrant was not issued, sources said. She went back a second time pleading for help, but the outcome was unclear because the records are sealed.

The mom then followed Williams after he got on a Manhattan-bound train and pressed him about their child, sources said. Williams, who was previously arrested for beating up the teen, then allegedly pulled a knife on her during the encounter, sources said.

Williams was arrested and brought back to the Bronx for questioning, but has not been charged, according to sources. He was then held at Rikers Island for custodial interference.

The child’s grandmother told PIX11 News she had warned police about Montrell’s disappearance, but was told it was legal because he was the father.