A post-mortem examination has failed to establish what caused the death of Daniel Spargo-Mabbs, the Croydon schoolboy who died on Monday after taking ecstasy.
Police are awaiting the results of further tests after the examination at Uxbridge mortuary yesterday proved inconclusive.
The 16-year-old, of Rymer Road, Addiscombe, died after taking the drug at what police called an "illegal rave" in Hayes in the early hours of Saturday.
The Archbishop Tenison's High School pupil suffered three heart attacks after taking MDMA, it emerged in court on Wednesday.
He was taken to Hillingdon hospital by paramedics at around 4am on Saturday believed to be suffering a drugs overdose.
The teenager was later transferred to Kings College hospital, where he remained in a coma until dying on Monday.
Two men accused of supplying the MDMA believed to have caused the Croydon teenager’s death appeared on court on Wednesday.
Nicqueel Pitrora, aged 18, of London Road, and Ryan Kirk, 20, of Beckenham appeared at Uxbridge Magistrates' Court charged with being concerned in the supply of class A drugs.
They were remanded in custody and will next appear at Isleworth Crown Court on February 5.
A 19-year-old man was also arrested and bailed until March pending further enquiries.
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