The agency says it became involved with the family of the victim, Jamar Cruz, in 2007 when Williams was accused of beating the boy with a belt.
Williams is the boyfriend of Cruz's mother, and later plead guilty to the beating.
The state met with the family for nearly a year before determining the home was safe in November.
The child died of blunt force trauma on Tuesday.
Williams is accused of repeatedly kicking and punching Jamar Cruz at their home in Ablett Village around 7:00 a.m. on Monday.
Police say Williams did not get medical attention for Cruz despite the boy's repeated complaints about pain throughout the day Monday.
An ambulance was called to the home Tuesday morning. Cruz was taken to Cooper University Hospital, where he was pronounced dead.
An autopsy conducted Tuesday concluded Cruz died from blunt trauma to the torso.
Williams was arrested after a police chase Tuesday morning, after Cruz was pronounced dead.
Authorities say an alert was put out for police to look for Williams around 8:30 a.m. Tuesday. His car was spotted by Magnolia Police on Route 30 at Warwick Road at about 9:25 p.m.
Police say he led officers on a chase onto I-295 into Bordentown, in Burlington County. He took exit 57A onto Route 130 North, before his engine blew out about 9:43 a.m. Williams was then arrested.
Jamar Cruz lived in the Ablett Villiage home with his mother, Williams, and a younger sibling.