A three-page report by the New Jersey Department of Children and Families issued late Friday afternoon says that state workers had little indication of distress from a Camden mother who later decapitated her son and that they could not have prevented his death.

The report issued by the department's commissioner, Allison Blake, said the agency used consistent and thoughtful practices to determine that Chevonne Thomas, 34, should regain custody of 2-year-old Zahree.

The report did note that some improvements were needed for better supervision, improved coordination of clinical assessments, and new guidelines for forensic evaluations.

"Overall, my review of this matter does not find evidence that [child protection workers] would have had any indication that Ms. Thomas was in distress or that they could have prevented this child's death," Blake wrote.

Thomas' parents, Wendell and Jerlaine Birch, disagreed. They had been awarded temporary custody of Zahree and said their daughter had been asking for help she never received. On Friday, they were surprised to learn that the report had been issued.

"I don't like the way they are handling this either," Wendell Birch said after reading the report.

Cecilia Zalkind, executive director for the nonprofit Advocates for Children of New Jersey, said that the report did not provide a full account of what happened and that the case needed outside evaluation.

"To me, it raises more questions than it answers," she said of the report.

Thomas struggled with drug addiction and severe mental illness. On Aug. 22, she smoked marijuana laced with the hallucinogen PCP (phencyclidine). She severed her son's head and placed it a freezer in her Parkside apartment.

She then called 911 and, in a sometimes-rambling conversation, said she had stabbed her son. Police arrived and found the boy's remains. When they entered the second-floor bedroom of the rowhouse, they found Thomas dead from a self-inflicted neck wound.

Custody had been taken away from Thomas in 2010 after police found her incoherent in Camden, the report said. She told authorities she smoked PCP and did not know where she left her baby, authorities have said.

Zahree was placed with his grandparents, who had previously helped care for him. Thomas lost custody a second time after she tested positive for PCP during a random drug test. Zahree was placed again with the grandparents.

"This was a complex child-protective-services case made more difficult by the mother's ongoing struggle with co-occurring mental-health and substance-abuse disorders," Blake wrote. "Ms. Thomas struggled with bipolar disorder and was taking medications to address this condition. However, she also admittedly used drugs."

Thomas was given treatment for her mental health and drug addiction, Blake wrote. The report notes that child care was provided for Zahree while Thomas received a number of services.

Thomas regained custody of Zahree on April 3.

The report does not release details about how often child-protection workers visited with Thomas, how often she was tested for drugs, or how frequently she was supervised interacting with her son.

The department was planning to close its case after meeting with Thomas for the last time July 3 and evaluating the case later that month.

Friday's report was the third statement issued by the department. Blake has not returned numerous calls seeking comment and has not fielded questions from reporters seeking more detailed information.

The department has been under the supervision of a federal judge since 2003 because of serious lapses in supervision that led to serious illness or fatalities among children.

An expedited review by the New Jersey Child Fatality and Near Fatality Review Board found that a reassessment from one of the psychologists would have been useful once the child was reunited with the mother.