Doctors knew my son's killer was a mentally ill skunk user

The father of a teenager stabbed to death by a paranoid schizophrenic whose condition was triggered by smoking "skunk" cannabis today asked why he was free to kill his son.

Tung Minh Le, 17, was stabbed once in the heart in an "unprovoked, unpredicted and inexplicable" attack as he left a West End nightclub.

His 18-year-old killer Chien Nguyen had become ill after starting to smoke cannabis at the age of 13.

He had been seen by a number of mental health doctors who believed the smoking of super strength skunk had triggered his psychotic behaviour.

By the time he killed Tung, he had also been arrested by police for possessing cannabis and carrying a knife.

Chien pleaded guilty to manslaughter by diminished responsibility at the Old Bailey on Friday and was sent indefinitely to a mental hospital.

But the victim's businessman father, Tung Phung Le, today demanded to know why Nguyen had been left free to kill.

Mr Tung, 40, said: "It does make me very angry that his illness was known and that he had been caught with knives and cannabis before but he was still on the streets to kill my son.

"If they knew he was ill why was he allowed to take drugs. Why wasn't he stopped? There is no guarantee that doctors will not release him one day and he will be free to kill someone else. The system does not work."

Minh Le, who had two brothers and two sisters, was born in Hong Kong after his parents left Vietnam in the early Nineties. He was brought to Britain as a baby and his parents settled in Deptford.

After finishing GCSEs, he was helping at his father's garden centre while studying at night school. But he was killed moments after he left the Thai Square club in Cockspur Street in the early hours of 23 February last year.

Chien, who had been at the club, saw him, drew the knife he habitually carried and "out of the blue" made a punch-like blow to Minh Le's chest.

Minh Le was taken to hospital but died six days later despite emergency surgery. He was the sixth of 30 teenagers to be killed violently in London last year. Chien, now 19, also born in Hong Kong to Vietnamese parents, fled and slept rough before handing himself in.

When officers searched his bedroom in Hackney, they found a meat cleaver, a claw hammer and two air pistols.

Mr Tung said the hatred felt towards the killer by him and Minh Le's mother Loan, 38, was not diminished because of his illness, saying: "We feel great anger towards his killer. "

East London NHS Foundation Trust admitted Chien had been seen by mental health services and said an inquiry into the case had been launched.