A young mother and her boyfriend have been charged with injecting her three young children with heroin, telling them the drug was "sleeping juice".

Police in Washington state say that the children's mother Ashlee Hutt, and Leeroy 'Mac' McIver, were found living with her children, aged six, four and two, among rat droppings, drug tainted needles and heroin.

Hutt, 24, and McIver, 25, are alleged to have plied her two daughters and one son with the highly-addictive drug at their house in Spanaway. Police discovered the children at the house in November 2015 after being alerted by a friend of the pair.

The children were subsequently removed from the home and are now living in foster homes.

Hutt appeared at Pierce County Superior Court on Monday (31 October) and faces child endangerment charges, including three counts of unlawful delivery of a controlled substance to a minor, second-degree criminal mistreatment and second-degree child assault.

McIver faces the same charges. The pair, who both deny the charges, have both admitted to having a heroin addiction.

According to court documents seen by The News Tribune, the oldest child told investigators the couple gave him "feel good medicine" which he described "as white powder which was mixed with water" which was injected with needles into him and his sisters.

It has been reported that two of the children tested positive for the dangerous drug, with puncture marks and bruising found to be consistent with needle injections.

Child Protective Services (CPS) reportedly found traces of heroin in the two-year-old girl's hair follicles after she was take from the property, another child tested positive for the drug while one did not.

Pierce County Sheriff's Department spokesman Ed Troyer told The Washington Post: "The kids lived in deplorable conditions. It wasn't a good living situation even without the issue of heroin. We unfortunately find kids living in deplorable conditions all too often, but we don't see parents intentionally putting drugs into kids."

"Some of the statements [the children] made were very disturbing about how they would get sleeping juice to go to sleep and it was injected into them by needle," Troyer told Kiro7.

It has not been made clear if McIver is the children's biological father and both Hutt and her McIver remain in custody.

In the US drug overdose has become the leading cause of accidental death, overtaking traffic accidents, last year.