A woman has been charged with murder after her eight-month-old baby died due to high contents of methadone and Xanax in her breast milk.

Sarah Ann Stephens, 32 is facing charges of second-degree murder and felony child endangerment because according to police, she breast-fed her son despite being aware of the high levels of prescription drugs in her system.

According to court documents, the Sacramento, California resident was apparently warned five months prior to the death of her baby in September 2012 to stop breastfeeding due to high contents of methadone in her baby's bloodstream.

Initially, the death of Stephens' baby, Ryder Salmen, was thought to be a case of Sudden Infant Death Syndrome (SIDS). However, two weeks later, toxicology results confirmed the baby died of a prescription drug overdose.

There is now criticism that the Child Protective Services (CPS) at Sacramento County failed to handle the case.

According to a report in Sacramento Bee, it took three months for the CPS to respond to Ryder's case even after he was considered at risk following high level of drugs in his blood when he was four-months-old.

Following the detection of the risk, a safety assessment was required to see if he should have continued living with his mother. However, according to a report in Mail Online, a CPS manager did not approve the safety assessment in this case until three months after it was created.

The report further said that on the same day the first safety assessment was approved, a second safety assessment was also created by the agency which said, Ryder's risk of being mistreated in future are low.

However, not long after the second assessment, a police report questioned CPS about Ryder's safety after Stephens' car went off the road while she was driving with Ryder in the back seat.

Records suggest, there was no further risk assessment from CPS after the car accident. Ryder died less than a month later.