A highly paid neurosurgeon who indulged his cocaine addiction, paid thousands of dollars for sex and was directly linked to the death of two prostitutes avoided detection and continued to practise at a private Sydney hospital.

Dr Suresh Nair worked at the Nepean Private Hospital in Sydney's western suburbs performing delicate operations, but spent much of his time leading a double life.

Between shifts, the Malaysian-born doctor was spending tens of thousands of dollars on marathon sessions with prostitutes and cocaine.

He would eventually be charged in connection with the deaths of two sex workers from cocaine toxicity and have his medical licence revoked.

Upon his arrest, many of his patients were horrified to learn of their doctor's extra-curricular activities.

For some, Dr Nair had botched their operations and left them with life-long ailments.

Letter spoke of 'serious concerns' about doctor's ability

Dr Nair had been on the impaired doctor's program since 2004 after self-reporting a problem with cocaine.

However, at the end of 2008, the NSW Medical Board (now the Medical Council) decided it was safe to stop drug testing the neurosurgeon.

That decision coincided with some major personal problems and Dr Nair's life began to spiral out of control.

Nepean Public Hospital was aware Dr Nair was again using cocaine, and withdrew his clinical privileges.

But he was cleared by the NSW Medical Board to work under conditions and on that basis continued to operate at the private hospital next door.

A Four Corners/Fairfax investigation has discovered that Nepean Public Hospital sent a letter to Nepean Private in April 2009 expressing concerns about Dr Nair's work.

The letter, from the head of neurosurgery at Nepean Public Hospital to the CEO of Nepean Private, said:

"We have serious concerns about Dr Nair's ability to practise. "The lack of onsite supervision may be exposing the patients to a risk about which they are not aware."

Healthscope, which operates Nepean Private, said it had no record of receiving the April letter.

The company said it relied on the decision of the NSW Medical Board, which in early 2009 cleared Dr Nair to practise under controlled conditions.

'It's so fun to be full of coke'

Sorry, this video has expired Suresh Nair speaks during a police interview in 2010

One young woman described to Four Corners the scene as she arrived at a party in Dr Nair's apartment in Sydney's eastern suburbs in February 2009.

"He had a plate with a mound of white substance – [a] white powdery substance – and it was quite forcefully directed our way," she said.

"He straight out said, 'Have some, take some, we're here to party'."

His common statement was "have you ever been so coked-up, it's so fun to be full of coke".

The next day, sex worker Victoria McIntyre, 23, died of a cocaine overdose after a booking at Dr Nair's apartment.

Police informed the Nepean Public Hospital but the NSW Medical Board, which manages the impaired doctor's program, was not informed of the young woman's death.

Dr Choong-Siew Yong from the Medical Council of NSW said that had the NSW Medical Board known about Dr Nair's involvement in the death, he would not have been allowed to continue practising.

"We would have had an immediate action hearing and in all likelihood he would have been suspended," she said.

Dr Nair was back working at the Nepean Public Hospital by late September 2009, after accepting strict conditions over and above those imposed by the NSW Medical Board.

On November 19, another young escort, Suellen Domingues-Zaupa, died at Dr Nair's apartment.

Ms Domingues-Zaupa, 22, suffered a cardiac arrest, but Dr Nair left her for dead as he went elsewhere to continue partying with other escorts.

Many questions have been raised about how the doctor was allowed to continue practising.

Dr Yong said not every regulatory system is perfect and the NSW Medical Board acted on the information it had on Dr Nair.

"In hindsight now we can see that he, at some stage, even under our program, was still affected by drugs. He was able to conceal that from us, from his colleagues, from his patients, from his supervisors," he said.

In May 2009, a psychiatrist said in a report to the Health Care Complaints Commission:

"It is my belief that Dr Nair is in stable remission from cocaine and alcohol abuse and that he is fully fit to practise medicine. I further believe that matters came before the Medical Board that would have been more suited to a casual chat between colleagues rather than a s.66 inquiry."

Business records from Liaisons brothel in Sydney show that in the nine months between the deaths of the two women the neurosurgeon spent more than $120,000 on drugs and sex workers.

'I can't remember not being in pain'

Patients who once trusted their doctor were horrified to learn of his activities away from the hospital.

Rhonda Taylor, who had scheduled operations with Dr Nair cancelled three times, said: "I'm still in disbelief to think that man was living that horrible life when he was operating on patients, on their brain, on people's backs."

Patient Carla Downes was operated on three times by Dr Nair.

It was not until last month that she found out what happened in her second operation when Dr Nair performed at the wrong level in her spine.

"My whole life has changed. I crawl up the stairs because I can't just walk up them one at a time. I can't remember not being in pain. I've been in pain for seven years.

"I'd ask, why did he do it? He had a duty of care to his patients."

After the death of Ms Zaupa in November 2009, the NSW Medical Board finally suspended Dr Nair's registration.

He would eventually plead guilty to one count of manslaughter and two counts of supplying prohibited drugs.

Dr Nair served more than four years behind bars for his crimes.

The neurosurgeon never obtained Australian citizenship, and on the eve of his parole date, July 31, Immigration Minister Scott Morrison cancelled his visa.

Dr Nair is expected to be deported to the country of his birth, Malaysia.