The Nepean public hospital sent a letter to neighbouring Nepean Private Hospital in April 2009 warning its management that, by allowing Suresh Nair to practise, it was potentially "exposing the patients to a risk about which they are not aware".

Yet two months before, the Nepean public hospital failed to inform the NSW Medical Board (now Medical Council) it had received a formal visit from police concerned about the death of a sex worker in St Vincents Hospital after a drug overdose at Nair's home and his links to cocaine.

The revelations form part of a joint Fairfax/Four Corners investigation, due to screen on Monday, that lays bare failings in the NSW health regulatory system.

The expose relates that, while the NSW Medical Board, the Health Care Complaints Commission, the Nepean public hospital and Nepean Private Hospital were all warned about Nair's chronic, continuing addiction over a five-year period, he continued to slip through the cracks and retain his certificate, leaving a trail of crippled victims and shattered lives, right up until his arrest in November 2009, when a second prostitute died in his home, also from a cocaine overdose.

Last month Nair was released from prison after serving four years after pleading guilty to one count of manslaughter and two counts of supplying cocaine. Immigration Minister Scott Morrison cancelled Nair's permanent residency status and he is now expected to be deported to his native Malaysia, where he has not lived since he was 10.

As far as his medical victims are concerned, it is a new beginning they can only dream of. "My whole life has changed," says Carla Downes, who still suffers because of botched surgery by Nair. "I crawl up the stairs because I can't walk up them one at a time."

Rhonda Taylor, another of Nair's patients whose 2009 spinal fusion went horribly wrong, says: "The impact Dr Nair and ... Nepean Private Hospital have had on my life is ... they've taken my life away."

In September 2004, Nair was suspended for eight weeks at Nepean public hospital after mandatory weekly urine tests exposed his cocaine use. In the board's 2005 annual report, Nair was identified as having a "severe impairment in the form of cocaine abuse/dependency" and "it is considered the practitioner must be suspended for the safety of the public until his rehabilitation was further progressed".

But it was not long before he returned to the operating theatre, under stricter conditions. When the board relaxed those conditions in 2008, Nepean public hospital again had to withdraw his clinical privileges. Fellow neurosurgeons also raised the alarm in January 2009 about his "inability to function as a consultant". One colleague described his surgical decisions as "often bizarre".

In February 2009, the rogue doctor's dual addiction to cocaine and sex proved fatal when an orgy with prostitutes led to the overdose death of Victoria McIntyre in his luxury Elizabeth Bay flat. While Nair did not inform anyone within the health system about that death, NSW Police did.

Former Kings Cross local area commander Tony Crandell said: "Detectives attended Nepean hospital in person to notify medical staff of the concerns that they had and the involvement of Dr Nair in this particular death and our concerns in relation to not only the supply of cocaine but his addiction to cocaine."

When asked why it chose not to inform the Medical Board of these developments, Nepean Blue Mountains Local Health District chief executive Kay Hyman said "it wasn't an issue ... that Suresh needed to answer to or was in any way considered a person of interest".

While the hospital was under no obligation to report the information, the chairman of the Medical Council's NSW committee, Choong Siew Yong, labelled its decision as "very regrettable". "We would have called an immediate action hearing and in all likelihood he would have been suspended," Dr Yong said.

Healthscope, meanwhile, which operated Nepean Private, said it had "no record" of receiving the warning letter from the head of neurosurgery at Nepean public, a copy of which had been obtained by Fairfax and Four Corners. A spokeswoman stressed the Medical Board had formally cleared Nair to resume operating, with restrictions, from January 2009.

As the failures between health authorities piled up, Nair continued to perform intricate brain and spine surgery at Nepean Private, and later returned to the public hospital. Outside work, he partook in drug-fuelled sex binges inside Sydney brothel Liaisons where he spent more than $140,000 in nine months.

As Fairfax previously detailed, official Liaisons room records show that less than half of those transactions were tallied as actual sexual services. The rest were listed as either "cash out", "advance" or "tip". According to a legal statement by a Liaisons insider, these were among the code words allegedly used to conceal Nair's cocaine transactions on the premises.

In November 2009, when a second escort, Suellen Domingues Zaupa, died in Nair's home from another fatal drug overdose, his life of destruction finally ended.

The Hand That Holds the Scalpel screens on Monday on the ABC at 8.30pm.

Twitter @eamonnduff

Timeline

1980: Immigrates to Australia from Malaysia, aged 10.

1992: Graduates from University of Sydney, aged 23.

2004:  Forced to have weekly urine tests while working at Nepean Hospital. Tests positive to cocaine. Receives an eight-week suspension.

2005: NSW Medical Board annual report refers to Nair's "severe impairment in the form of cocaine abuse/dependency". He continues to operate on patients.

2008: Nepean public hospital suspends Nair again after complaints from colleagues are referred to the NSW Medical Board.

2009: Escort Victoria McIntyre dies on Valentines Day from cocaine supplied by Nair. The tragedy is repeated nine months later when prostitute Suellen Domingues Zaupa also dies of an overdose. In between, Nair spends $140,000 hosting numerous cocaine-fuelled orgies at Liaisons brothel while maintaining his role at Nepean Private Hospital and later at the adjacent public hospital again. After being charged with murder and manslaughter, his practising certificate is finally revoked in November.

2011: Sentenced to five years and three months' jail for manslaughter and two counts of supplying cocaine.

2013: His prison term is reduced on appeal.

July 31, 2014: Released from prison but has his visa cancelled. Is expected to be deported to Malaysia in the coming weeks.

SLIPPING THROUGH THE CRACKS:

2004: Tests positive to cocaine at Nepean public hospital. Receives eight-week suspension.

2008: Clinical privileges withdrawn by the hospital with colleagues later raising alarm about his "confusing judgment" and "bizarre" surgical decisions.

2009: Police attend Nepeain public hospital and inform hierarchy about the first escort overdose death in Nair's home, venting additional "concern" about Nair's cocaine links. The hospital chooses not to forward this information to the Medical Board. He continues working.

2009: Nepean public hospital sends a letter to Nepean Private Hospital confirming it has barred Nair due to "serious concerns" about his ability to practice. However, the private hospital says it never received the letter. Nair continues to work at the private hospital. By the time he was arrested in November, he was back operating at both Nepean hospitals.