A heartbroken father believes cannabis drove his son to take his own life.

Gregory Thibeault told the Croydon Guardian his son Geoffrey's long-term habit triggered mental health problems which led the 34-year-old dad-of-three hanging himself.

Speaking from his home in Sandpiper Lane, Selsdon, Gregory said he hoped his son's story would encourage others to give the drug up.

He said: "There's a lot of talk about cannabis being a soft' drug, but I believe it can trigger things in certain people and I believe this is what happened in Geoff's case.

"I am absolutely convinced that cannabis altered something in his mind and nobody is going to tell me any different. I believe cannabis was ultimately responsible for his death."

An inquest into Geoffrey's death at Croydon Coroner's Court heard how the painter and decorator's GP urged him to give up cannabis on March 24 after he complained of paranoia, believing his telephone was bugged and that he was being monitored by police.

But on April 16, Gregory called police to his son's home in Milton Road, Croydon, after he failed to turn up to a family lunch.

Gregory added: "We were all sitting in the restaurant waiting for him. When he didn't turn up I knew something was wrong.

"He'd told me the day before that he would eventually kill himself and I asked him not to do that to us."

Police broke into the property, which had been barricaded from the inside, and found Geoffrey hanging from the staircase.

The hearing heard officers found cash left neatly piled on top of the washing machine as well as a note asking for forgiveness for what he had done.

A postmortem showed no trace of cannabis in Geoffrey's system at the time of his death.

Gregory added: "Geoff had smoked cannabis since his early 20s. The ironic thing was that at the time of his death he was off the stuff. But I guess by then it was too late, the damage had already been done.

"Geoffrey was separated from the mother of his children but he was a happy-go-lucky guy. Cannabis changed him.

"The week before his death he had been on holiday with us and he seemed happier. But he was obsessed with this idea that his phone and ours were being tapped and that people were watching him. He was due to see a doctor about his state of mind."

Recording an open verdict last Thursday, coroner Dr Roy Palmer said he couldn't be sure Geoffrey was mentally capable of forming the necessary intention to kill himself.