The mother of a 4-year-old boy -- found bruised, battered and unconscious in his Crown Heights home -- has been charged with murder.

Police arrested Myrna Chen Phang, 25, and her boyfriend, Steven Dadaille, 26, Saturday, and charged the pair with second-degree murder in the death of Jayden Lancere.

Officers responded to a 911 call from Phang Friday afternoon, and found little Jayden unresponsive. He was taken to Kings County Hospital Center, where doctors pronounced him dead.

Medical Examiners ruled the death a homicide Saturday, attributing it to blunt impact injuries to the torso and extremities.

The boy's devastated father told the Daily News he hadn't seen his son in two weeks; since his divorce from Jayden's mother, he's only had weekend custody.

Meanwhile, sources say Phang and Dadaille played the blame game, pointing the finger at each other in written and video statements, while professing their own innocence.

A spokeswoman for the New York City Administration for Children's Services would not say if it had a case history on the little boy, adding his case was now under investigation.