The Independent Commission Against Corruption sent shockwaves through the Sydney legal community on Thursday when  it announced it was inquiring into allegations the silk and her eldest son, Stephen Wyllie, told his girlfriend, Sophia Tilley, to "pretend to have chest pains" to stop police officers breath-testing her at the scene of a car crash in May.

Ms Tilley, 25, allegedly took the advice of her 26-year-old boyfriend and Ms Cunneen, a deputy senior Crown prosecutor. All three are being investigated over whether they were seeking to pervert the course of justice - an offence punishable by up to 14 years in jail.

Queensland barrister Alan MacSporran, QC, a former Queensland Parliamentary Crime and Misconduct Commissioner, has been drafted in to head the inquiry to avoid any conflict of interest. Public hearings will start on Monday, November 10, and are expected to run for three days.

Ms Tilley pleaded guilty to running a red light on October 28 at Waverley Local Court, in an incident that appears to be unrelated to the current investigation. She is due to be sentenced the same day the ICAC begins hearings in the inquiry, codenamed Operation Hale.

Ms Tilley, a marketing coordinator at Laing & Simmons in Double Bay, is the daughter of eastern suburbs identity Barry Tilley and his former wife Georgia. According to News Limited reports, Ms Tilley has breast implants and is expected to give evidence that there was a medical reason why she had chest pains.

Ms Cunneen has been a Crown prosecutor since 1990 and was appointed deputy senior Crown prosecutor in 2002.

In July she endured torrid questioning at the Royal Commission into Institutional Responses to Child Sexual Abuse concerning her advice in respect of dropped charges against Scott Volkers, a former national swimming coach.

In advice to Queensland authorities, she had described one alleged assault as "trivial" compared with the nature and duration of most sexual assaults that came before the courts. Ms Cunneen said she was referring to what a jury was likely to think.

The 55-year-old's long-running friendship with Steve Fletcher, one of the nation's biggest gamblers and a person with underworld connections, has raised eyebrows in legal circles.

Mr Fletcher, who employed Ms Cunneen's son Stephen, was the subject of a Police Integrity Commission inquiry which investigated Mr Fletcher's use of the identities of many NSW police officers to open hundreds of betting accounts to disguise his betting activities after he was banned from placing bets with many internet betting agencies.

Ms Cunneen introduced Mr Fletcher to one of the detectives embroiled in the PIC inquiry, homicide detective Tony "Soup" Williams. The detective, Mr Fletcher and Mr Wyllie enjoyed a gambling jaunt to Las Vegas for Mr Wyllie's 21st birthday.

One police officer told the PIC inquiry that he was aware of "whispers" that Mr Fletcher corruptly used inside information in his betting activities.

Although the final report in Operation Montecristo is yet to be released, the PIC's annual report says three people involved in the inquiry have been referred to the Director of Public Prosecutions for possible criminal charges. There was no criticism of Ms Cunneen at the PIC.

Mr Fletcher, who bets up to $1 million a week, was disqualified from betting for a year by Racing Queensland after an investigation found he had prior knowledge that a jockey would ride to lose. The inquiry found Mr Fletcher and the jockey were in regular telephone contact. However, the disqualification was overturned on appeal.

In 2012, former premier Barry O'Farrell appointed Ms Cunneen to preside over the special commission of inquiry into claims of interference in police investigations of alleged paedophile priests in the Hunter region.

Attorney-General Brad Hazzard said the Director of Public Prosecutions, Lloyd Babb, SC, had advised that Ms Cunneen had "agreed that it is appropriate for her to stand aside and to have no active involvement in any current prosecution or future prosecution until the resolution of the ICAC hearing, whereupon the situation will be reviewed".

"It is important to recognise that any individual appearing before ICAC has the presumption of innocence and Ms Cunneen, as with any other NSW citizen, has an absolute entitlement in that regard," Mr Hazzard said.