DENVER -- The Denver Department of Human Services will undergo a third-party review of its child protection practices after 7NEWS Investigators uncovered disturbing details about the department's handling of cases of children who were eventually killed -- Chandler Grafner and Neveah Gallegos.

Chandler was the 7-year-old child who was allegedly starved to death by his guardians. Niveah was the 3-year-old girl who was found in a ravine in West Denver this week.

Denver Human Services had at one time opened child abuse investigations involving both children.

A 7NEWS investigation found that Denver Human Services knew more than a year ago that then 23-month-old Neveah showed physical signs of sexual abuse.

Her mother's boyfriend, a registered sex offender, was the only suspect, yet Denver Human Services did not go to court and remove the child from the mother. Instead they opened a voluntary case to monitor the family. The case was later closed as unfounded because the girl's mother would not cooperate with the investigation.

Now both her mother, Miriam Gallegos, and her mother's boyfriend, Angel Montoya, are charged with the girl's murder.

In Chandler's case, a Denver Human Services case worker went to his house after his teacher called a hot line and reported concerns over the boy’s frequent absences and other possible signs of abuse.

Chandler was living with his guardians, who are not biologically related to him. John Phillips and his girlfriend, Sarah Berry, both face charges of first-degree murder and child abuse resulting in death.

Chandler weighed just 31 pounds when he died in May.

A state department reviewed the case and concluded that the three agencies responsible for investigating Chandler's welfare didn't do an adequate job or share information. The state said the Denver Department of Human Services failed to get reports from Jefferson County after it was told of alleged abuses in January.

The state Department of Human Services along with the Kempe Center, and the private Annie E. Casey Foundation will review all aspects of the Denver agency that deals with abused and neglected kids.

"Denver Human Services takes very seriously our role in protecting children. Our team works diligently to protect children every day of the year and we are constantly striving to improve our practices. I have asked for a complete, thorough third-party review of our child protection practices," said Roxane White, manager of Denver Human Services.

The review is expected to take two months and will be presented to the public when it's completed.

"Among the procedures the review will include a review of hot line calls, investigations of allegations of abuse or neglect, voluntary services, filing of dependency and neglect petitions, and follow-up services to children and families," White said.

The state Department of Human Services is also involved in a fatality review of the 3-year-old's death.

The Denver Department of Human Services had to do something more as it has now come under tremendous pressure for the handling of these cases, said 7NEWS Investigator John Ferrugia. This appears to be an effort to get a credible group to determine what, if any, systemic changes need to be made.

Denver Human Services received 11,164 calls of suspected abuse or neglect in the last year, had 4,384 children in out-of-home care and provided in-home services to 3,350 children. In addition 1,469 children were placed with adoptive parents.