A young Brooklyn felon out on probation allegedly delivered fatal blows to his girlfriend’s 2-year-old son because the toddler had been crying, law-enforcement sources said yesterday.

Natalie Garner, 21, left the child, Jaquil Degraffenreid, with her boyfriend, Tyree Wright, 19, and his family when she left his Cypress Hills home for her catering job at about 9 p.m. Friday, the sources said.

That night, Wright called Garner at work to say the boy was sick, and she rushed to his house.

Garner told cops that when she got there, at 2 a.m., she tried to play with her son, but he was acting strangely.

She said she called 911 when he slipped into unconsciousness.

Little Jaquil was rushed to Kings County Hospital, where he was pronounced dead.

The hospital notified cops when staffers saw bruises on the boy’s forehead, collarbone and torso.

When questioned by detectives, Wright told them that he hit the boy twice because he was crying, the sources said, adding that Wright repeated his admission in a videotaped interview with the Brooklyn District Attorney’s Office.

Garner has not been charged with any crime.

She told detectives that a ceramic pot fell off a shelf and hit her son while he was playing in the Shepherd Avenue apartment at about 7 p.m. on Friday, a police source said.

Police did not say whether such an accident actually happened.

“It broke my heart in pieces, a little boy suffering like that,” said a neighbor, Ivan Sanchez, 51, who added that the family moved in just weeks ago.

“How do you kill a child? It’s just insane,” Sanchez said. “He’s evil. I hope he gets what he deserves.”

Wright was charged with assault and acting in a manner injurious to a child on Saturday.

An autopsy performed yesterday showed that the little boy died from lacerations to his liver and pancreas and internal hemorrhaging, according to the city Medical Examiner’s Office.

His death was then classified as a homicide, and the charges against Wright may be upgraded, sources said.

Wright has a lengthy criminal record.

He has five prior arrests, including assault and robbery, and was jailed in 2009 and 2011.

When Wright allegedly beat the child, he was on probation for robbery.

“It’s tragic, what happened,” said next-door neighbor Julio Batista, 49. “The baby was 22 months and couldn’t defend himself.”

The Administration for Children’s Services interviewed other youngsters living in the apartment and found no signs of neglect or abuse.

Garner’s last known address is a homeless shelter on Amboy Street in Brownsville.

Additional reporting by Reuven Fenton and Frans Koster