As Whitney Houston’s drugs-ravaged body lay cold under a sheet in her suite at a Beverly Hills hotel, elsewhere in the building a Grammy Awards party was being thrown by her long-time mentor Clive Davis.

Later, while guests including Britney Spears, Diana Ross, Jane Fonda and Sir Richard Branson were swanning out of the front entrance, Whitney Houston’s corpse was being hustled ignominiously out of a side door.

It’s difficult to imagine how Whitney Houston’s demise – in a bath last February – could have been more melodramatic. But now startling new claims suggest an extraordinary twist.

Paul Huebl, a Los Angeles private investigator, who has probed celebrity drugs cases and suspicious deaths, sensationally alleges that 48-year-old Whitney Houston was murdered by two thugs sent by high-powered East Coast drug dealers to collect on a $1.5 million debt.

Former police officer Paul Huebl says he has presented the FBI with what he insists is compelling evidence that Whitney Houston was targeted by the two men, who were part of a group of scruffily dressed hangers-on. He says the pair were unknown to most, but not all, of Whitney Houston’s huge entourage, which repeatedly visited her hotel room in her final days.

Incredibly, Paul Huebl even claims the men were captured on the hotel’s CCTV going into the singer’s suite – No.  434 – at the luxurious Beverly Hilton around the time she died.

Whitney Houston was discovered face down in a scalding bath by her assistant, who had left her for just 45 minutes while she went out to run errands. When paramedics arrived, Whitney Houston was unresponsive. They performed CPR for about 20 minutes before declaring her dead.

A coroner ruled that the death of the greatest singer of her age had been due to accidental drowning, with heart disease and chronic cocaine abuse listed as contributory factors. An “acute dose” of cocaine was found in her system as well as a cocktail of other drugs, including marijuana and prescription sedatives.

As theories swirled about Whitney Houston’s untimely death, it emerged she was in so much debt that she was having to ask for $100 handouts from her friends. (Her hotel suite had been paid for by Clive Davis.)

But could her mountain of debt really have led to her death?

Paul Huebl explained the scenario he insists accounts for unexplained details in the official coroner’s report.

He said about new evidence he has unearthed.

Paul Huebl will not say who hired him to look into Whitney Houston’s death but does confirm it is not Pat Houston, Whitney’s sister-in-law and one-time manager who claimed the star was the victim of a murder conspiracy – only to suddenly, and unaccountably, change her mind.

He said: “Every indication is that it’s a murder. I’ve got some evidence that is pretty glaring, and I’ve turned it over to the appropriate law-enforcement agency.”

Paul Huebl says unnamed informants have told him that surveillance video footage exists of the two men he claims are involved, entering Whitney Houston’s suite shortly after 2:45 p.m. on the day she died – February 11 – while her assistant was out.

He believes they demanded the money she owed their bosses, and when she refused to give it to them, “things got physical”.

Although Whitney Houston’s assistant informed police that the last thing she told the singer before she went out was to have a bath, Paul Huebl thinks Whitney was thrown in the water by one or more assailants. And what might have started out as an attempt to scare her, ended in murder.

The evidence for the alleged struggle, he says, lies in the coroner’s report. The coroner, for instance, noted that a large area of skin on Whitney Houston’s lower back was burnt off – so-called “skin slippage” – by the scalding bath water. The water was so hot that six hours after she died it was 93.5F (33 C).

Even someone high on cocaine wouldn’t “willingly” get into a bath that hot, says Paul Huebl, who adds: “She obviously had <<help>>.”

As for the report’s revelations that Whitney Houston had injuries on her forearms and hands, Paul Huebl claims these are “consistent with her having a pretty nasty struggle and consistent with classic defence wounds”.

“There were bruises on her arms and shoulders, a cut on her upper lip, scrapes to her nose and forehead, and lacerations to her scalp.”

Paul Huebl sensationally alleges that 48-year-old Whitney Houston was murdered by two thugs sent by high-powered East Coast drug dealers to collect on a $1.5 million debt

In fact, Whitney Houston had so many injuries it looked as though she’d been in a boxing match, he says.

“Call this an accident if you want, but it doesn’t make sense to me.”

He believes that after Whitney Houston was killed, her assailants ransacked her suite, took money, drugs and jewellery, and left before her assistant returned.

Pal Huebl, whose investigation was first reported in the National Enquirer, is by no means the first person to have been puzzled by Whitney Houston’s death and her bizarre behavior in her final days.

In the early hours of her last day, a stoned-looking Whitney Houston was seen on her hotel balcony, shouting: “I’m tired of this s***!”

Some people have wondered if it was a cry of desperation from a superstar who realized her precious voice – with its famous three-and-a-half octave range – was gone forever.

But Paul Huebl believes it was a cry from the heart over the harassment she was getting to repay the money she owed her drug dealers.

He says he was told by an informant that Whitney Houston had earlier taken possession of a new supply of cocaine and been partying with a small group of people, including her killers, in her suite until around 4:00 a.m. When she refused to pay them, they left and returned later that day with fatal consequences.

As Paul Huebl notes, Whitney Houston had a “risky lifestyle” including heroin and crack-cocaine abuse, and inevitably surrounded herself with others involved in that criminal world.

As to the identities of her alleged killers, Paul Huebl clearly has his suspicions. However, he will say only that Whitney Houston’s alleged murder could have its roots in more than one state. He claims drug-world sources have told him that people from New Jersey and Georgia – states where Whitney Houston has lived – were involved.

Paul Huebl adds that he approached the FBI because it has no connection with the police force that undertook the original investigation and because it is responsible for cross-state crimes.

When asked why Beverly Hills police have not acted on the allegedly damning hotel CCTV evidence, which presumably they must have seen, Paul Huebl pointedly says: “I should ask them.” (Neither the FBI nor the Beverly Hills Police Department have commented on his claims.)

However, he told the National Enquirer he believed the police and coroner were “happy to sweep Whitney’s death under the rug, calling it accidental and closing their investigation”.

Paul Huebl also believes that at least some of Whitney Houston’s entourage “know what happened”.

In April, Beverly Hills police concluded that foul play was not involved. Detectives based their decision on the coroner’s findings that the singer’s death was due to accidental drowning and, in part, the result of cocaine ingestion and a heart condition.

The 41-page coroner’s report found that Houston was submerged in bath water for nearly an hour, and that her personal assistant had last seen her alive between 2:35 p.m. and 3:00 p.m.

So should we give any credence to Paul Huebl’s theory? Certainly, it’s easy to dismiss it as the product of a fevered imagination, or cynical publicity-seeking. Except that in Whitney Houston’s case, her life had become such a sordid train wreck that anything seemed possible by the end – including vengeful drug dealers prepared to maim and kill.

Whitney Houston’s final public performance two nights before her death spoke volumes about how low she’d sunk from the days when the world and Kevin Costner swooned at every quivering note of I Will Always Love You in The Bodyguard film.

She staggered on stage at a tiny Hollywood club called Tru, drunk, puffy-faced and dishevelled, to sing a dreadful one-minute duet of Yes, Jesus Loves Me with soul singer Kelly Price.

Whitney Houston ended up in a fight with another singer, then left with her hangers-on and blood trickling down her leg.

She spent the next night (her last) in the bar of her hotel, drinking heavily and treating staff and fellow guests to her trademark behavior of wandering around, flailing her arms, doing handstands and burbling unintelligibly. The following afternoon she was dead.

Her long-time friend Robyn Crawford said afterwards: “I don’t know what kind of pressure she was putting on herself.”

While family members and close friends insisted Whitney Houston had shaken off drugs, others – including therapists who spoke to her relatives – claimed her loved ones had cynically ignored her drug abuse because they were relying on her as their breadwinner.

Whitney Houston was by her own admission “no angel”, however much her marketing people tried to manipulate her image.

Friends revealed that the singer was taking drugs before she even met Bobby Brown, the ex-gang member, convicted criminal and drug addict who became her husband and supposedly ruined her.

In 2006, a few months before the couple got divorced, Bobby Brown’s sister Tina sold shocking pictures of Whitney Houston’s bathroom in her mansion, which the star had turned into a crack den. Her teeth had fallen out from drug use, and she was so incontinent she was wearing nappies.

Associates told newspapers that Whitney Houston and Bobby Brown used to cruise the streets of New Jersey and Atlanta in chauffeur-driven limos, looking for crack.

In the Nineties, Whitney Houston was reported to have paid $750,000 to one drug dealer alone.

According to Globe magazine, she owed $1.5 million to drug suppliers when she died.

Whether or not the murder theory has any credence, Whitney Houston’s death was a particularly pitiful end for a star who, thanks to her legions of black and white fans across the world, represented a color-blind show business world.

Her demise became a polarizing moment in much of America. Amid the national grieving, some commentators condemned Whitney Houston as a disgusting junkie who squandered her huge talents and deserved no eulogies.