Owen Kinghorn died after ecstasy overdose
A 15-year-old boy died when an overdose of ecstasy caused "cardiac arrhythmia", a coroner has concluded.
Owen Kinghorn's body was found in a field behind a cricket club in Ashford, Kent, on 7 September last year.
Assistant coroner Sonia Hayes said pathologists found 4,128 micrograms of MDMA per litre in his blood.
She said: "Concentrations at much smaller levels have been sufficient to cause death in adults."
The coroner said police had not been able to identify who supplied Owen with the drugs.
After the hearing, Owen's mother, Rachel Kinghorn, described her son as the "heart and soul of our family" and said they were "empty without him".
She described MDMA as "almost like a silent killer; it's out there but no-one is doing anything to stop it".
And she said that "while there is breath in my body I will not rest until there is justice for Owen".
'Typical of young men'
The inquest at the Archbishop's Palace in Maidstone heard how Ms Kinghorn thought her son had been staying at a friend's house for a sleepover.
When she realised this was not the case she called the police, who began a search for him.
Ms Hayes told the inquest Owen was "typical of young men of his age" and "young people do not always tell their parents the truth".
Det Sgt Martin Glynn from Kent Police told the inquest the force had found evidence on Owen's phone to suggest he had researched the drug.
His friends told police that, after taking it, he was running around and sweating before leaving the group.
Ms Hayes said: "Owen had no understanding of the quantity he was taking. He [thought] he was having fun.
"I counsel any young person not to take these substances and gamble with their life."