A file note written by then NSW Crime Commission boss Phillip Bradley shows the plan to promote the current NSW Police Commissioner from head of internal affairs to deputy commissioner in December 2001 prompted a flurry of high-level discussions.

It says on December 13 Mr Bradley briefed the then police ministry chief, Les Tree, about an investigation into a telephone conversation Mr Scipione had with Nick Kaldas, the current Deputy Commissioner who was at the time being bugged by Mr Scipione's unit.

Mr Bradley recounts that then Police Integrity Commission boss Terry Griffin "said that there was a potential problem with [Mr Scipione]".

He records that after further discussion with then police commissioner Peter Ryan, it was "decided that, in the light of the urgency of the matter, we could progress the investigation somewhat".

Mr Scipione's promotion was announced the next day, on December 14.

The file note has emerged on the eve of a parliamentary inquiry, beginning on Thursday, into Ombudsman Bruce Barbour's investigation of a police bugging scandal involving Mr Scipione, Mr Kaldas and another deputy commissioner, Catherine Burn.

At issue is a 2003 internal police inquiry, Strike Force Emblems, that probed allegations of illegal bugging by NSW Police internal affairs and the NSW Crime Commission in 1999-2001, known as Operation Mascot.

More than 100 police officers and a journalist were placed under surveillance, despite some affidavits used to secure the warrants from the Supreme Court containing no or false information.

The Emblems report - never officially released but details of which have been revealed by Fairfax Media - is sensitive because Mr Scipione and Ms Burn worked in internal affairs at relevant times and Mr Kaldas was one of those bugged.

Greens MP David Shoebridge, who obtained a copy of the file note, said it highlighted the way Mr Scipione was given favourable treatment in sharp contrast to Mr Kaldas who remained under investigation for several years.

"With the political decision to appoint Scipione having been made, there was a sudden rush to clear him of any potential damage from the police bugging scandal," he said.

"While other police have waited more than a decade to have their names cleared, it appears that Scipione's investigation was finalised in an afternoon through the combined efforts of the PIC, the Crime Commission and police internal affairs."

"The question has to be asked why is there one road for certain police and a far harsher one for others?"

A police spokesman said: "Prior to any promotion within the NSW Police Force, candidates must receive a clearance from the Police Integrity Commission. That process was undertaken in this instance."

The Herald does not suggest any of those involved in the investigation acted improperly.