A FORENSIC scientist has revealed how a mental health patient blew up a block of flats in Canterbury.

Investigations showed Paul Avery disconnected a gas pipe leading to the meter in his ground floor flat in Tenterden Drive.

Minutes later a massive explosion shattered the block and 30-year-old Mr Avery was left seriously injured with 70 per cent burns. He died a month later in a specialist burns unit in East Grinstead.

At an inquest the reason why Mr Avery disconnected the pipe remained a mystery. But police, who investigated the explosion in June, last year, discovered he had recently been watching a rented sci-fi video called Ring of Fire.

However, because Mr Avery never regained consciousness before his death, officers were unable to question him about his actions and intentions.

A previous incident was also revealed when he had inexplicably turned the water supply off to another flat.

However, Det Ch Insp Tim Smith said there was no evidence anyone else had been involved in the gas blast and Mr Avery was the only one present in his flat at the time.

Mr Avery had previously worked as a Seeboard cable layer but was unemployed because of his mental health problems.

He had been a patient at St Martin's Hospital in Canterbury and was being treated as an out-patient for depression and paranoia.

His psychiatrist said he had expressed suicidal thoughts in the past but was on medication. But it was also revealed he had recently missed two doctor's appointments.

Forensic scientist Dr Christopher Foster told the hearing he had come to the "firm conclusion" the pipe in the flat leading to the gas meter had been deliberately disconnected at a safety valve and was the source of the leak.

He said it was also consistent with the high rate of gas build up in the flat which could have taken as little as three-and-a-half minutes to reach ignition levels.

But no evidence could be found as to what actually triggered the blast, although it could have been something as simple as a match being struck or and electric appliance or light being switched on.

Eight people were injured in the explosion, which also badly damaged neighbouring homes.

Among them was Transco engineer Mark Tarbuck who, by coincidence, was mending a meter in a flat above Mr Avery.

He smelt gas as he left the property and got a special gauge to measure the levels around the ground floor of the block. Suspecting it was coming from the ground floor flat, he knocked on the door but got no answer.

He said: "I then did a letter box test by putting the probe into the letter box and got a reading of 10 per cent, which is the highest I have recorded in a property in 25 years in the job. I noticed there were four locks on the door and a neighbour told me, 'the bloke in there is mad, you won't get in'."

Mr Tarbuck said he went back to his van parked nearby to alert his bosses and tell them to call the police. But as he returned to the flats with the intention of evacuating the building he was hit by a blast.

He said: "I was 20ft away when there was a blue flash and a massive explosion. The next thing I knew I was 20ft away with burns and cuts."

The blast was heard by Mr Avery's parents who live in Broad Oak Road.

His father, Robert Avery, said: "It didn't really register at first until we got a phone call from some people on the estate to say that Paul's flat had exploded."

Mr Avery drove around to Tenterden Drive to find the emergency services at the scene and paramedics treating his badly burned son.

"He recognised me and I kept talking to him but he was completely dazed. But we never spoke again because he never regained consciousness although we kept talking to him in hospital," he said.

Mr Avery said his son had showed no signs of wanting to harm himself in the days before the tragedy. Mr Avery's brother, Ian, said he had also received a text from him just two hours before the blast and there was no hint in the message of his intentions.

The jury returned a verdict of death by misadventure.

In a statement after the hearing the Avery family said: "This has been a terrible tragedy. Paul was a much-loved son and brother and cared for very deeply by his family and friends.

"The inquest has left many questions unanswered that perhaps only Paul himself could have given the answer to."