A two-year-old Irish girl died after drinking the heroin substitute, methadone, in London, the Old Bailey heard yesterday.
Jasmine O'Shaughnessy died within hours of drinking from a bottle of the drug which had been prescribed to her mother Louise (40).
The court was told that Jasmine had taken at least 40 milligrams - a fatal dose for an adult not used to the drug.
Ms Louise O'Shaughnessy, of Rosebank Walk, Camden, north London, pleaded guilty to three charges of child cruelty to Jasmine, and two charges relating to another child.
She admitted two offences of failing to stop Jasmine having access to methadone and another of failing to seek prompt medical attention for her.
Two charges of manslaughter and giving Jasmine the drug were left on file. Mr David Walters QC, prosecuting, said expert analysis of Jasmine's hair showed she had swallowed methadone on more than one occasion in the previous year. It also showed she had been around when heroin and cocaine had been smoked.
Mr Walters said a 999 call was made from the untidy maisonette where Ms O'Shaughnessy lived, at 12.30 a.m. on March 31st, 2001.
A paramedic found Jasmine's naked body at the bottom of some stairs. He said: "She was naked, she was not breathing, she had no pulse and her lips were blue."
Later, Ms O'Shaughnessy told officers she believed the toddler had drunk from her methadone bottle seven hours earlier.
She said: "She must have seen me taking it and copied me."
Ms O'Shaughnessy said she realised what had happened when Jasmine woke her up. She was smiling and saying "Mummy, Mummy".
After being sick, the child had gone to sleep and appeared to be recovering until an hour or so before help was summoned.
Ms O'Shaughnessy, who had been arrested for having crack cocaine a week before, disappeared in August last year after being bailed in connection with the death. She was re-arrested in February after being caught shoplifting.
Mr Walters said Ms O'Shaughnessy came to Britain with Jasmine in 1999 from Ireland.
She was prescribed 50 milligrams a day of methadone, but had been given 100 milligrams for the weekend.
She had been supported by social services, a health visitor and her GP, but had missed appointments or not taken Jasmine with her when she was seen.
She was remanded in custody until January 7th.