Seventeen hours after Man Haron Monis walked into Sydney's Lindt cafe and ordered a cup of tea and cake, he forced shop manager Tori Johnson to kneel.
He then shot him in the back of the head without further warning.
Moments later, Sydney barrister and mother of three Katrina Dawson was killed by ricocheting police bullets in the volley of fire that followed.
Such horrifying events have rarely unfolded so publicly, NSW Coroner Michael Barnes noted as he opened an inquest into their deaths in the Sydney siege.
"The protracted nature of the siege; its morbid suspense and the explosive climax must have made manifold the grief of the families of the hostages who died," Mr Barnes said on Thursday.
While some doubts may always remain as to what drove Monis to carry out the attack, the inquest hopes to explain virtually everything else that happened that day.
What they know already is that Monis entered the cafe at about 8.33am on December 15, counsel assisting the coroner Jeremy Gormly SC said.
He was dressed in long camouflage pants, a white t-shirt and a black jacket and was carrying a large black backpack and blue plastic bag, armed with a sawn-off pump action shotgun.
He ordered a piece of chocolate cake and tea and, half an hour later, when seated at a table that afforded a view of the whole cafe, asked to speak to the manager.
Those who knew Mr Johnson could tell he was stressed by what Monis was telling him, Mr Gormly said.
Mr Johnson told another staff member in a low voice, "I need you to go get my keys from the office and lock the doors. We're closed. Everything is ok. Tell the staff to be calm".
Once the doors were locked, Monis put on a vest and bandanna, stood up, pulled out the shotgun and - according to one account - announced: "This is an attack, I have a bomb".
At Monis's behest, Mr Johnson called Triple 0, saying Australia was under attack by Islamic State.
By 9.51am, police were on the scene.
Monis ordered the hostages to move to the northern wall of the cafe and told some to hold an Islamic flag up to the windows.
After making several threats to shoot in the following hours, he fired the first of his five shots after some hostages fled the cafe in the afternoon.
Then at 2.14am on December 16, he ordered Mr Johnson to kneel on the cafe floor.
Holding the barrel 75cm from the back of his head, Monis fired and killed the cafe manager.
A police marksman witnessed the shot and the order was made to force entry.
Eleven "flash-bangs" were let off by police - creating a cacophony of 99 sounds and lights inside the cafe.
Two police officers fired 22 shots, as armed tactical response officers stormed in.
Ms Dawson was struck by six police bullet fragments which ricocheted into her body.
She died shortly after, Mr Gormly said.
At least two police bullet fragments hit Monis in the head, with 11 others peppering his body.
It seems Monis was trying to re-engage another round when he died, the inquest was told.
To help build a picture of why and how Monis carried out this attack, a range of witnesses will give evidence in a number of hearings.
This includes hostages as well as an independent team - made up of UK and interstate experts - that will assess the NSW police response.
"If there were defects in the management of the siege they will be exposed," Mr Gormly said.
Monis's psychiatric profile, his associations and political and religious activity, as well as his relationships, will all be examined.
How he came to be granted bail despite facing charges relating to the murder of his wife will also be looked at.
The inquest was adjourned with a future hearing date and location yet to be set.
