Mayor Bill de Blasio says Monday's death of a 6-year-old boy in Harlem, who was an apparent victim of child abuse, is unacceptable, but many are asking how Zymere Perkins' case slipped through the cracks. NY1's Grace Rauh filed the following report.

Six-year-old Zymere Perkins was on the city's radar. But it was not enough.

The boy died Monday after he became unconscious in his Harlem apartment and his mother brought him to St. Luke's Hospital. His body and head were covered in bruises.

His mother and her boyfriend have been arrested and charged with acting in a manner injurious to a child.

"There were warning signs. They were clearly looked at by a variety of agencies. How that didn't lead to a different outcome is what I don't understand," said Mayor Bill de Blasio. "And I find it an unacceptable outcome, and I'm going to demand answers from everyone involved."

Sources told the Daily News that the boy's mother, Geraldine Perkins, had been accused of child abuse five times. Police say the mother's boyfriend, Rysheim Smith, allegedly beat the boy with a broom handle.

"Many times, there are warnings, and the question is, what do we do with those warnings?" de Blasio said. "And if there's a problem with the law, let's change the law. If there's a problem in the way agencies communicate, let's change that."

The mayor says this case reminds him of the death of Nixzmary Brown, a 7-year-old Brooklyn girl who was beaten, tortured and murdered by her stepfather in 2006. The city's agency for child services was aware the girl was possibly being abused. Her death prompted major reforms.

At the time, de Blasio was chairman of the City Council's General Welfare committee and held a hearing on the case, which NY1 carried live.

"We have to re-evaluate all of our policies, including what allows us to remove a child when there is a danger," de Blasio said at the time.

In 2014, just over a week into de Blasio's mayoralty, a 4-year-old boy, Myls Dobson, died. His babysitter allegedly beat him to death and was charged with murder.

The mayor urged New Yorkers to call and report when the think a child may be in danger.