The state's police chief stepped into the witness box at the inquest into the 2014 siege on Wednesday afternoon and began his much-anticipated evidence.

Counsel assisting the coroner Jeremy Gormly, SC, grilled Mr Scipione about an email he sent to police commanders on the night of the siege suggesting - or "directing" as Mr Gormly submitted - a YouTube video put up by the hostages be taken down.

Mr Gormly's focus was also on a single sentence a scribe made on the night of the siege.

It read "DA plan to occur as a last resort - COP".

"DA" stood for "deliberate action", the kind of tactical assault police launch to catch the offender off guard, while "COP" referred to "commissioner of police".

The scribe made the entry after a 10.57pm phone call on December 15, 2014, between Mr Scipione and Assistant Commissioner Mark Jenkins, who was the police commander at the end, and critical point of, the siege.

The entry cuts to the heart of where the decision lay to delay police from entering the cafe on their own terms rather than waiting until gunman Man Monis executed hostage Tori Johnson and only then carrying out an emergency action plan or "EA".

It also deals with whether an executive officer had any influence on operational decisions in response to the siege.

Asked about the entry, Mr Scipione said he called Mr Jenkins after the latter took over as the police commander, to check on his welfare.

He said he didn't use the words - "DA plan to occur as a last resort" - as he had no reason to.

Mr Scipione suggested that Mr Jenkins said it.

"It is not an area I would have played a role," he said.

"He has obviously come back and said in terms of the DA being a last resort. These were his words.

"They weren't my words."

Pressed on whether Mr Jenkins would have had the DA on his mind that night, Mr Scipione said he couldn't answer that and suggested he ask Mr Jenkins.

"I can't, Mr Scipione, he can't remember it either," Mr Gormly quipped.

"It is not that I don't want to help you sir, I do," Mr Scipione replied.

Mr Scipione said he did not know how Mr Jenkins came to raise the DA, which was never approved, but it was captured by a scribe on Mr Jenkins' side.

"I can assure you I know I wouldn't be asking or telling Jenkins or any other commander that a DA was a last resort, simply because that's not my responsibility, that is not my role," he said.

Like Deputy Commissioner Catherine Burn, who finished giving her evidence on Wednesday morning, Mr Scipione stressed it was not his role at the siege to give operational decisions or recommendations.

Mr Gormly put it to Mr Scipione that it must have played on his mind what degree of risk the NSW public was prepared to accept in the management of the siege.

"The one thing that was driving me was the safe release of every single person from the stronghold," he said, adding the thought "consumed" him.

He was also asked about an email he sent at 11.59pm to Mr Jenkins and acting Deputy Commissioner Jeff Loy about a YouTube video made from within the Lindt cafe.

Mr Gormly suggested he was "directing" the removal of the social media clip when he said, "Let's move to have it pulled down from You Tube as soon as possible."

Mr Scipione finished the email with "I'll leave it to you and others."

Mr Gormly put it to Mr Scipione that this would have been taken as a direction from him and that such an order conflicted with Mr Scipione's insistence that he had no operational role in the siege.

It might also have had an impact on the siege stronghold and aggravating Monis, the inquest heard.

However Mr Scipione denied it was an order.

"That was not the way it was intended," he said.

The inquest continues.