A 22-year-old barman who died from a cocktail of hard drugs could have been injected with heroin when he was unconscious, his mother told an inquest today.

Linda Thompson also expressed fears that her son's body was was cleaned up and drug taking paraphernalia was disposed of before the emergency services arrived at his north Belfast home.

James Thompson, known to friends and family as Jim, was found to have heroin, cocaine, cannabis and Diazepam in his system when he died in the upstairs bedroom of his house in Harrisburg Street in the early hours of a Sunday morning last October.

A part-time barman in the Grove Tavern owned by his family, the coroner's court in Belfast heard he had been in treatment for drink and drug misuse and had been subject to threats from paramilitaries for outstanding debts.

A man and woman who were with him at the time of his death were due to give evidence at today's inquest but did not appear - prompting coroner Brian Sherrard to issue a penal notice for them to attend to face questions on a later date.

In the evidence that was presented, Mrs Thompson told the court that while she knew her son drank heavily and had indulged in soft drugs, she questioned whether he would have willingly injected himself with heroin.

"There were two needle marks on the back of Jim's right hand," she said.

"But he was right handed so why would they be on his right hand if somebody else didn't do it?"

She claimed the other drugs in his system would have knocked him out and he wouldn't have woken if someone had injected him while he was unconscious.

"Jim would have slept through a hurricane," she added.

But expert medical witness Dr Alistair Finlay said it was highly unlikely Mr Thompson would not have roused if someone was trying to inject him when he was asleep.

"If he was asleep and someone tried to inject him the pain would have caused a reflex action," he said, adding that the concentration of sedatives in his body was not high enough to make him unwakeable.

In regard to the injection marks on his right hand, the doctor said it was commonplace for drug users to agree to inject each other.

"There was nothing to suggest that drugs were injected without his consent," he said.

In response to Mrs Thompson's claims that needles had been removed from the scene, a PSNI detective revealed that an extensive search of the property and surrounding area had failed to recover any items associated with heroin use.

Detective Constable Mark Gillespie said: "We couldn't find any needles, which was something that was of a concern to us."

During the hearing, Mrs Thompson also queried why her son had no shirt on when paramedics arrived at the house. She said he was heavily built and shy about revealing his body around other people.

"Somebody took the shirt off him when they were disposing of the needles and other paraphernalia," she claimed.

"They took his shirt off because it might have been incriminating."

The only person in the house at the time of the incident who appeared in court was Mr Thompson's best friend Hugh Kirkpatrick.

However, Mr Kirkpatrick said his friend had stayed in his room all evening with the man who had failed to turn up in court and he had only spoken to him briefly at around 6pm and again at 10pm, at which point he said Mr Thompson was slurring his words.

"That usually meant he had taken a couple of Diazepam," he said.

While the two men remained in the bedroom, Mr Kirkpatrick said he watched football on TV downstairs with another friend before going to bed.

He said the first he knew something was wrong was when the woman who had also been with Mr Thompson, but who was not in the house before he went to bed, woke him at around 3am.

"When I went into the room he was lying on the bed, he had no top on and he was in boxer shorts," he said.

"He was grey and wasn't breathing."

Mr Kirkpatrick said he knew his friend had a drug habit but had no idea he had progressed to heroin.

"I knew he smoked cannabis, I knew he took cannabis but there was no indication he took heroin," he said.

Detective Gillespie said prosecutors had recommended that charges be taken against Mr Kirkpatrick in regard to cannabis found in the property in the wake of the incident.

He said drug charges were also being brought against the man and woman who had been in Mr Thompson's company when he died.

Mrs Thompson said her son acknowledged he had problems with drink and drugs but always thought he could handle them himself.

"He was a big lad and thought he was invincible," she said.

A pathologist's report indicated the cause of death as mixed drug toxicity.

Coroner Sherrard adjourned the inquest to reconvene again when the two absentees were in a position to give evidence.