A MUCH-LOVED teenager who had a fascination with fire probably died after burning toxic substances, a coroner’s court has ruled.

However, the family of 13-year-old Mason Douglass say not enough was done to investigate after experts failed to pinpoint what triggered his tragic death.

Teesside Coroner’s Court heard that the popular Acklam Grange pupil died from inhaling fumes after burning things when home alone.

On October 5 last year, a neighbour heard Mason shouting for help and saw him behaving uncharacteristically in his garden, where he appeared naked and unsteady - a sign, the court heard, of an altered mental state.

Shortly afterwards, his mother Suzzanne Douglass returned from work to find him unresponsive at their Acklam home.

She administered CPR but despite her efforts and those of medics, Mason died later that evening and his death was later attributed to anaphylactic shock.

An inquest held on Wednesday, November 23 heard that a plastic Ferrero Rocher box containing a slightly burned silica gel packet was found at the scene, while Mason’s school uniform smelled of smoke.

A video on his phone filmed days earlier showed Mason staring into the flame of a lighter.

It is believed Mason inadvertently inhaled toxic fumes from the chocolate box and suffered a fatal reaction within 90 minutes.

No drugs or alcohol were found in his body and, despite a battery of tests, experts remain uncertain as to which chemical was responsible for the tragedy.

Detective Sergeant Matthew Hollingsworth of Cleveland Police said: “It may have been butane, burned plastic or silica gel balls but at this stage, we will never know.”

DS Hollingsworth said the force had investigated claims that Mason may have stolen chemicals from a science lesson but his school maintained all chemicals were kept secure.

At the inquest, assistant coroner Joanne Wharton gave a verdict of death by misadventure.

She said: “It seems Mason inhaled something at his home when he got back from school, probably related to his tendency to play with fire.”

Mason’s devastated family are taking action against the police, saying that not enough was done to preserve crucial evidence and claiming it took months for officers to collect the box experts believe is linked to Mason’s death.

Ms Douglass said: “I’m not happy with the investigation, there are too many inconsistencies.

“If the box had been taken sooner, it might have been a different story - I feel let down by the police.”

She thanked Mason’s friends for their support, saying: “I want to thank those kids for being such good friends and keeping his memory alive.

“As a parent, you never think about something like this and I’ve beaten myself up about it but we can’t watch our children 24/7 - he was just a normal boy.

“When you’re burning something, you never know what’s in it or what chemicals it can produce.”

A spokeswoman for Cleveland Police confirmed the force was investigating a complaint and said that further comment would therefore be inappropriate.