Cannabis addict gripped by paranoia stabbed a stranger to death in the street



Victim: Devoe Roach was stabbed through the heart

A cannabis addict gripped by paranoid psychosis knifed a teenager to death in the street seconds after meeting him for the first time, a court has heard.

Imran Khan, 21, admitted the manslaughter of 17-year-old Devoe Roach but denies murder on the grounds of diminished responsibility.

Khan stabbed Mr Roach through the heart less than a minute after bumping into him in the street last March.



Psychiatrist Dr Mark Lyall told the Old Bailey that Khan was in the 'grips of a major psychiatric episode' at the time of the killing.

Khan, whose mother is schizophrenic, has a genetic pre-disposition to mental illness which was emphasised by his regular heavy use of 'skunk'.



'It is likely Mr Khan has paranoid schizophrenia, it is sometimes difficult to tell when people are in the early stages of severe mental illness and that is the position with Mr Khan, but I am sure he has paranoid psychosis,' said the doctor.

Jurors were told Khan looked at the world through a 'paranoid filter' which impacted on the way he reacted to life.

He heard voices in his head and believed people were out to kill him, it was said.

In the months before he stabbed Devoe, he had removed the handle from the outside of his bedroom door so it could only be opened from the inside.

Khan, who is married with a young daughter, had left his wife 'petrified by his erratic behaviour'.

Dr Lyall interviewed his grandmother and aunt who said he would mumble and talk to himself, bang his head against walls, stare and laugh uncontrollably to himself.

He had trouble sleeping, ate little and spent much of his time in his bedroom smoking weed. He armed himself with a knife whenever he went out in public.

Dr Lyall said: 'Mr Khan had two major risk factors for the development of paranoid psychosis.

'There is a strong family history of paranoid psychosis which afflicted his mother and also an aunt and on top of that there is his persistent and heavy use of strong cannabis.'



In an interview with the psychiatrist, Khan revealed he first took ecstasy when he was 11 and smoked cannabis from the age of 12.

His use of skunk was 'particularly heavy' in the three years leading up to his arrest for murder, the court was told.

He smoked two joints before killing Devoe last March, having woken up at 6.30am and left the house to avoid going out when it was busy.

Paranoid: Imran Khan, 21, killed teenager Devoe Roach, who he just met in the street, after years of smoking 'skunk' cannabis (file photo)

Khan told Dr Lyall he became paranoid that Devoe and his friend were watching him as he crossed Stamford Hill, north London.

They confronted each other when Devoe asked: 'What are you looking at?' 'He said he tried to walk away but Mr Roach followed him,' the psychiatrist said.

'He was panicking, paranoid, he felt anxious, his palms were sweaty, his heart was breathing fast and his was breathing quickly.

'He couldn't remember exactly what happened next but he recalls Mr Roach running his mouth.

'Mr Khan took out the knife he carried with him. He told me he wasn't angry and didn't swing the knife around however Mr Roach fell over and before he got up Mr Khan ran off.'



The court heard he had 'changed greatly' in the 15 months before the stabbing, according to his aunt and grandmother who cared for him.

His strange behaviour forced some of his extended family to cut short visits to his home.

At the time of the killing his grandmother had flown to Pakistan and left him with his wife, who he called 'an enemy', and child in the care of his aunt.

She had tried repeatedly to contact his GP about his behaviour 'but no help was forthcoming'.

When he was arrested, a doctor who examined him said Khan suffered from psychosis 'due to excess skunk use since the age of 13'.

Dr Lyall said: 'It is difficult to tell for certain what is likely to have caused the paranoid psychosis. He had a very strong genetic predisposition to psychosis and the use of cannabis caused the illness to develop.'



Michael Holland QC, prosecuting, has told jurors they would have to decide whether Khan's condition impaired his responsibility for the killing.

Devoe, who lived with his mother in Stoke Newington, bled to death after the knife wound penetrated one of the major chambers of his heart.

A doctor then performed open heart surgery on the pavement, but the teenager was pronounced dead at hospital just after 11am.

Khan, from Stamford Hill, north London, denies murder. He will not be giving evidence.

