Director of Public Prosecutions Shane Drumgold SC is expected to be the first witness called when the independent probe begins public hearings on Monday.

His evidence is due to be followed by that of Mr Lehrmann's barrister, Steven Whybrow SC, during what the inquiry has described as the first of four "modules".

Executive director Helen Banks said the first module, which will focus on the Director of Public Prosecutions, was expected to run until Tuesday next week.

The inquiry is due to then take a break until May 22, with details of the remaining three modules yet to be confirmed.

Mr Drumgold led the high-profile prosecution of Mr Lehrmann, a former Liberal Party staffer who denied raping ex-colleague Brittany Higgins at Parliament House in 2019.

After Mr Lehrmann's trial was aborted because of juror misconduct last year, Mr Drumgold discontinued the case due to fears for Ms Higgins' mental health.

The fallout from the criminal case was swift and dramatic, with civil lawsuits filed and complaints lodged.

Mr Drumgold was at the centre of the storm, accusing police of "cherry-picking" evidence and inappropriately interfering in his decision-making.

Those claims were among several explosive allegations the territory's top prosecutor made in a letter to ACT chief police officer Neil Gaughan.

In the letter, he stated his support for a public inquiry into the case's handling.

Mr Drumgold will finally get his wish on Monday, with all eyes set to initially be on him as board of inquiry chairman Walter Sofronoff KC begins hearing evidence from the key players.

Among the tasks the ACT government has set for Mr Sofronoff, a former Queensland judge, is getting to the bottom of whether Mr Drumgold breached, or failed to act in accordance with, his duties in relation to Mr Lehrmann's case.

The key issues include Mr Drumgold's decision to take the matter to trial in the first place, with the Australian Federal Police Association previously calling for an explanation after it was revealed investigators held concerns about the strength of the evidence and how some of it was obtained.

He will also be grilled about his preparation for the trial and his conduct during it, his decision to discontinue proceedings, and how his office released the letter he wrote Deputy Commissioner Gaughan under freedom of information laws.

While Deputy Commissioner Gaughan has not publicly addressed whether that was appropriate, he has told his staff he was not consulted before the letter was sent, without the personal details of officers redacted, to the Guardian.

Mr Drumgold has hired Mark Tedeschi KC, a high-powered former NSW prosecutor, to represent him at the inquiry.

If Mr Sofronoff ultimately finds Mr Drumgold acted inappropriately, the ACT government has asked him to investigate possible "reasons and motives".

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The chairman's task will be similar in relation to the conduct of police officers, who are set to appear later in the inquiry.

The independent probe will also consider whether ACT Victims of Crime Commissioner Heidi Yates acted appropriately in terms of the support she provided Ms Higgins during Mr Lehrmann's criminal case.

The inquiry's public hearings will take place at the ACT Civil and Administrative Tribunal, but those wishing to follow the proceedings have been encouraged to watch a live stream on its website because there will be "very limited seating".

Mr Sofronoff was initially required to report his findings to the ACT government by the end of June, but the deadline was recently extended by a month.

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