Senior Constable Paul Withers was quick to the scene of the Lindt Cafe siege after the first triple zero call from inside.
Cafe manager Tori Johnson had called triple zero at 9.41am. Sen Const Withers was responding to a call on police radio at 9.46am and arrived three minutes later.
The highway patrol officer was instrumental in conveying to other officers what was happening inside the cafe, after entering the foyer of the building in Martin Place which housed the cafe and coming face-to-face with hostage Marcia Mikhael, who was standing with her hands up at the glass doors.
Wearing a bulletproof vest, he used eye signals and hand gestures to communicate with Ms Mikhael.
His contribution to the unfolding police operation was invaluable, providing to authorities the fact that Man Monis was the sole gunman while also working to protect innocent members of the public from the beginning of the siege.
Sen Const Withers is seen in footage presented to the inquest into the siege creeping behind pillars, walls and doors in an attempt to conceal himself in the building's foyer, which leads into the Lindt Cafe.
He will be among three police to give evidence on Wednesday at the inquest into the December 2014 siege.
The inquest will also hear from witnesses who attempted to enter the cafe on the morning of the siege, unaware of what was unfolding inside.
The inquest has already seen CCTV footage of the moment police stormed the Lindt Cafe after gunman Man Monis fired a shot at escaping survivors before turning a sawn-off shotgun at Tori Johnson.
Cafe manager Tori Johnson was forced to kneel and place his hands behind his head. He was then shot in the back of the head by Monis.
"Don't move, everything will be fine," Monis then told hostages as he stood over Johnson's slumped body.
It was after this flash of shotgun fire that police sniper Sierre 3 radioed in 'White Window 2, hostage down'. Within minutes, the siege would be over.
The inquest is set to hear whether police should have acted immediately after Monis fired his sawn-off shotgun at the escaping hostages, instead of waiting for the death of Johnson.
It was a mere two minutes from the time Monis shot Johnson to the time he was shot dead by police.
Monis sustained multiple gunshot wounds to the head, shoulder, back, chest, buttocks and foot, the inquest heard on Tuesday.
The inquest heard that police officers cannot recall how many shots were fired at Monis, but there is evidence of a total of 22 bullets.
That message was immediately relayed to authorities. About 30 minutes later, the same message was sent to a Lindt & Sprungli phone number.
"What police did on receiving word of these messages is a matter that will be addressed in evidence,” Callan told the inquest.
Newly released audio from a secret police bug placed inside the Lindt Cafe during the Sydney siege has revealed teenage survivor Jarrod Morton-Hoffman tried to bargain with gunman Man Monis to release a pregnant hostage.
Raw and grainy audio heard Monis laughing off a request from Morton-Hoffman to release pregnant Sydney barrister Julie Taylor.
"If you let the pregnant lady go I'll print you a flag," Morton-Hoffman pleaded as Monis discussed his desires for more Islamic State propaganda to be used.
Monis simply laughed off the suggestion.
"I’ll print you one hundred, I’ll paint everything," Morton-Hoffman continued.
Hostage Selina Win Pe called police at 1:12am in a desperate bid to convince negotiators to shut off lights surrounding the cafe.
"I'm going to get shot in 15 minutes if you don't have these lights turned off," she told a police negotiator.
"You don't know how close I just came. Could you please have these lights switched off? I have 15 minutes before I get shot with a rifle."
The inquest heard gunman Monis may have had an accomplice and possible hopes of escape.