DENVER -- The death of 3-year-old Neveah Gallegos is not only being investigated by Denver police, it's now being investigated by the Colorado Department of Human Services.

Last year, both Denver Human Services and the Denver Police Department investigated reports that the girl was sexually assaulted.

The only suspect in that case, Angel Ray Montoya, is now behind bars, accused of killing her and dumping her body in a ravine.

In July 2006, Neveah was found to be bleeding in her diaper after a stay with her mother's boyfriend -- Montoya.

She was taken to the doctor and then examined at the Denver Family Crisis Center, where both Denver police and the Denver Department of Human Services got involved.

When examined at the crisis center, sources familiar with the case told 7NEWS that doctors confirmed that the child showed signs of sexual assault.

The girl, who was 23 months old at the time, had been penetrated.

Sources confirm that Montoya, a convicted sex offender, had been caring for Neveah the day the bleeding started.

But Neveah's mother, Miriam Gallegos, would not cooperate with police, saying her boyfriend wouldn't have hurt the child.

Denver police sources said Montoya later called detectives, denying he had hurt the child and said he did not want to talk further.

Without the cooperation of the mother, police could not pursue the case.

Meanwhile, the Denver Department of Human Services did not take the girl away from her mother, even though officials suspected her boyfriend had sexually assaulted Niveah.

Instead Denver Human Services opened what is called a voluntary case, asking Gallegos to cooperate by cutting ties with her boyfriend and living with Niveah at her mother's home.

Sources indicate Gallegos agreed and also began working to improve her parenting skills and get a job. Sources familiar with the case said Gallegos told her case worker Niveah was not around Montoya and that she had not seen him.

7NEWS has learned Denver Human Services never interviewed Montoya.

7NEWS Investigators have confirmed that Denver Human Services closed the case in January 2007, saying, despite the documented physical injuries to Neveah, the allegations of abuse were unfounded.

Gallegos was free to resume her relationship with the convicted sex offender.

So questions remain: how could the case be closed and unfounded with such injuries to a toddler and why was the case voluntary rather than filed with a court?

A court may have removed the child from her mother and required more and longer supervision before custody was returned to Gallegos.

CALL7 Investigator John Ferrugia spoke with an assistant city attorney who represents the Denver Department of Human Services.

The city attorney did not deny any of the facts in the story and said, "I am frustrated because I cannot respond and the agency is frustrated it can't respond ... But the law does not allow us to discuss details of the case."

With the state investigation going forward, Denver Human Services' role in the case will be examined, just as it was in the case of Chandler Grafner, the 7-year-old boy who was starved to death.

The investigation will be made public.

All day on Tuesday a steady stream of people stopped to pray or cry at two memorials for Neveah created near the ravine where police found her body on Monday.

A candlelight vigil is planned at a nearby church on Wednesday.