BOSTON (AP) – The Department of Social Services commissioner on Thursday defended how his agency handled the case of a 4-year-old girl who died of a prescription drug overdose, saying the child “didn’t fall through the cracks.”

Rebecca Riley was found dead at her Hull home Dec. 13. Her parents, Michael Riley, 34, and Carolyn Riley, 32, pleaded not guilty on Tuesday to a charge of first-degree murder.

“The department completed its inquiry … did not drop that inquiry, but completed that inquiry with assurances from medical experts that the care was appropriate and sufficient,” Spence said. “This child didn’t fall through the cracks.”

An autopsy found the cause of death as a lethal combination of several prescription drugs, including a fatal dose of Clonidine, which Rebecca had been taking for attention deficit hyperactivity disorder, prosecutors said. She also had been prescribed medication to treat bipolar disorder.

Prosecutors called the overdose intentional, but defense lawyers said the parents were only following a doctor’s orders in the medications they gave their daughter.

Spence said DSS investigated a complaint last July about overmedication of the mother, Rebecca and two older children, who were placed in foster homes after the girl’s death. DSS was assured by medical professionals that the medications were within appropriate guidelines, Spence said.

Spence said the agency again investigated in October. He said the family came in for a visit to DSS and appeared safe and that the agency tried to make a subsequent home visit in late November, but Carolyn Riley “resisted and evaded.”

He said DSS on Dec. 12 decided to schedule a surprise visit to the family’s home, but Rebecca died the next day before the visit could take place.

Spence said DSS has had trouble pulling together a team of doctors and medical experts to consult on cases involving medical issues and children.

He said many in the medical community are leery of consulting on DSS cases because of the high profile nature of the cases, the potential liability involved and the difficulty of gathering medical records for children under the supervision of the department.

In response to those concerns, Secretary of Health and Human Services JudyAnn Bigby said she would be appointing a doctor within the next few days to provide medical consultation to DSS on an interim basis as the agency develops longer-term systems for medical review and oversight.

“The Department of Social Services needs the capability to provide a medical assessment for cases in which there are questions or concerns about medical care that children receive independent of DSS,” Bigby said in written statement.

On Wednesday, the psychiatrist who prescribed Rebecca’s medication agreed to stop practicing medicine until the case is resolved. Dr. Kayoko Kifuji’s attorney, J.W. Carney, told reporters that his client did nothing wrong and is cooperating with investigators.

Kifuji never contacted DSS, Spence said.

On Beacon Hill, House Speaker Salvatore DiMasi issued a statement calling the death of Rebecca Riley “gut-wrenching” and saying it showed the importance of the House’s push to improve child protection services in Massachusetts.

The newly-formed House Committee on Child Abuse and Neglect has held 12 hours of hearings in recent weeks on issues facing the Department of Social Services, high-risk children and the reporting of abuse. The Committee is set to issue a report next month.

“More can and should be done and the House is committed to taking a lead role,” DiMasi said.

On Wednesday, the House chairman of the Joint Committee on Public Health said he’ll hold an oversight hearing to examine the practice of prescribing medication to children. Rep. Peter Koutoujian, D-Waltham, said he’ll seek legislative measures to better protect children.