The partner of Tori Johnson, one of two hostages killed in the 2014 Lindt Cafe siege in Sydney, says he is "very disappointed" with the accounts of the police operation delivered by NSW Police Commissioner Andrew Scipione and his deputy Catherine Burn, suggesting they have "betrayed the community".

Yesterday, the two senior officers appeared before the coronial inquest into the deaths of Mr Johnson and another hostage, Katrina Dawson.

Mr Johnson's partner Thomas Zinn emailed a statement to 7.30, saying Commissioner Scipione and Deputy Commissioner Burn "were given the opportunity to present their credible approach … to differentiate from the previous accounts heard and to save the reputation of the NSW Police".

"Unfortunately, the opposite was the case," Mr Zinn said.

Mr Zinn is incredulous that the two senior officers suffered memory loss of critical elements of the siege, writing that "they could remember attending briefings where snacks and water were discussed, but cannot recall content of telephone conversations about DAs [Deliberate Action plans] and the threat to the lives of innocent citizens".

Commissioner Scipione and Deputy Commissioner Burn initially resisted calls to testify at the inquiry, saying they had nothing to do with the decisions made on the night.

Andrew Scipione and Catherine Burn initially resisted calls to testify ( AAP: Mick Tsikas, David Moir )

NSW Police also initially wanted all police testimony heard behind closed doors.

The coroner hearing the inquest, Michael Barnes, ruled that the evidence would mostly be in open court and called the two senior officers to appear.

"How can anybody trust our police when they are reluctant to give evidence, suffer from amnesia, serve non-publication orders and contradict their own evidence?" Mr Zinn said.

"We are not talking about the officer on the street here, we are talking about commanders in charge of thousands of armed officers meant to protect the community from harm.

"They have betrayed their own system that they are employed to protect and by doing so, betrayed the community."

Mr Zinn conceded that Mr Johnson may have died that night, whatever decision was made, but said "what adds to the pain is the lack of a plan that night".

"God help Australians if we ever face a terrorist with more than a sawn-off shotgun," he wrote.

In their appearances at the inquest, both Commissioner Scipione and Deputy Commissioner Burn maintained that they made no orders or recommendations during the Lindt Cafe siege operation.

But Commissioner Scipione admitted he bore final responsibility for its handling.

"I wasn't responsible for decisions that were made but in terms of the buck, it stopped with me," he told the inquest.

Thursday would have been Mr Johnson and Mr Zinn's 16th anniversary together.

Space to play or pause, M to mute, left and right arrows to seek, up and down arrows for volume. Watch Duration: 13 minutes 15 seconds 13 m What role did NSW's top cops play in the siege?

Thomas Zinn's statement to 7.30: