The woman who would become the infamous "Lawyer X" was under pressure from client Tony Mokbel and she wanted out.

For years police suspected she was making a mockery of the legal system and when her emotions boiled over, now-detective sergeant Paul Rowe was there to offer an escape.

All she had to do was dish the dirt on Mokbel and help bring down his criminal enterprise.

Sgt Rowe had no idea when he took the August 2005 phone call just how deep Ms Gobbo had got herself.

A conversation unfolded that was so strange about her connections with the underworld, and the pressure she was under from Mokbel for protection, that Sgt Rowe met her to get it again on a secret recording.

There was no way police could have foreseen the type of involvement she had with the underworld or her reach into organised crime - not in her capacity as a barrister but as an associate and friend, he said.

Ms Gobbo's involvement was blurred to the point Mokbel was using her "extensively" to evade prosecution and capture.

"She would be sent in at his behest to represent persons and in doing so prevent them from rolling on Mokbel," Sgt Rowe said.

She was giving him an inside look at what police were investigating, the evidence available and who their informers were, he said.

That had long been the suspicion of members of the Major Drug Investigation Division, of which Sgt Rowe was then a part.

She was protecting herself, Mokbel and probably other lawyers, he said.

And now she was confirming it on tape - first in a secret recording in a brief conversation at court and in a longer "venting" conversation later the same day.

She so desperately had to get information off her chest that over an hour they barely had to ask questions as she skipped from one admission to another.

There were details about Mokbel's activities and fears she'd "crossed a line" into criminal activity herself, and was worried about her reputation in the legal fraternity.

Ms Gobbo was looking for a way out, so Sgt Rowe and his colleague Steve Mansell offered one.

If she got on board with police, she could avoid pressure to do things for people involved in serious crimes including homicides and major drug trafficking.

"I'm not saying she doesn't have a level of responsibility for her own behaviour, but she was under enormous pressure and looking for a way out - a hand of friendship," Sgt Rowe said.

Ms Gobbo was visibly upset and he confessed it was a strange thing for a barrister to admit to police, especially two she didn't know.

"This is not a case of us just pouncing on an injured mouse crawling on the floor, this is just an unbelievably unexpected situation," he said.

She agreed as long as her safety was maintained, to which police agreed.

Later Sgt Rowe admitted there was "no way we perceived that we would make things worse for her".

He disagreed that it was inappropriate to use her to then spill dirt on her client's criminal dealings.

Here was a barrister acknowledging "manipulation" of the criminal justice system for Mokbel - how could that ever not be appropriate to disclose, he asked.

They were investigating Mokbel and she was confessing to "trying to square away a witness" so he wouldn't be charged. And she was doing it under pressure from Mokbel himself, she told them.

"All we cared about was criminal activity that was going on, that was right in front of our faces," he said.

She and others had made a mockery of the justice system for years and on this day, for whatever reason, he said she boiled over in front of him.

Australian Associated Press