Australia Sydney
Katrina Dawson (L) was killed during the siege as well as cafe manager Tori Johnson (R). Ms Dawson was 'hit by ricocheting police bullet.'Twitter

One of the hostages killed by a gunman during the Sydney siege was forced to kneel on the floor before being shot in the back of the head, an inquest has heard.

Cafe manager Tori Johnson was killed by gunman Man Haron Monis using a sawn-off pump action shotgun before police stormed the Lindt cafe in Martin Place - in the city's financial district - and killed him.

"At least two bullets, police bullets or bullet fragments hit Monis in the head and 11 other bullets, police bullets or fragments hit him in the body. It seems he was killed instantly, " Jeremy Gormly, a lawyer assisting the coroner, told Glebe Coroner's Court.

"Mr Johnson was made by Monis to kneel on the floor of the cafe. After a short lapse of time, Monis simply shot him without further notice or warning in the back of the head.

"The end of the barrel was about 75 cm from his head at the moment of discharge. Mr Johnson is believed to have died immediately."

Another hostage barrister Katrina Dawson, 38, was also killed in the police cross-fire as they entered the building.

Remnants of a police bullet ricocheted off the walls before hitting Dawson.

"One fragment struck a major blood vessel," said Gormly.

"She lost consciousness quickly and died shortly afterwards."

The inquest has revealed the full timeline of the shocking day of events on 15 December - including when Monis first ordered and ate a piece of chocolate cake and a tea before he began his terrifying attack.

He asked to speak to the manager Johnson who asked one of the employees to lock the doors.

Monis then stood up, putting on a vest and bandana and told staff: "This is an attack. I have a bomb."

He then ordered hostages to hold a flag described as being Islamic up to the windows.

The inquest aims to establish whether deaths could have been avoidable and if it should have been treated as a terrorist event.

It will also examine the motivations of Man Haron Monis.

There were eighteen people who were taken hostage.

Timeline of events

DECEMBER 15

8.33am: Man Haron Monis enters the Lindt Cafe on Martin Place. He wears camouflage pants, black jacket, baseball cap, black backpack, and carries a plastic bag, Monis carries a hidden pump-action shotgun sawn off at butt and barrel

He eats chocolate cake and drinks tea, then moves to a table with a view of the whole cafe

9.03am: Monis asks to speak to the manager.

Tori Johnson sits down with Monis.

Staff says Johnson appears stressed during the conversation.

Johnson says to a staff member something like, "I need you to get my keys - lock the doors - we're closed - everything is OK - tell the staff to be calm".

The doors to the cafe are locked.

Monis puts on a vest and a bandanna, stands up, produces the shot gun and declares, "This is an attack. I have a bomb".

He orders staff and customers to move to northern wall of the cafe.

Monis orders hostages to hold a flag described as being Islamic up to the windows.

9:44am: Monis tells Johnson to call triple-zero.

Following Monis's orders, Johnson tells operator Australia is under attack by Islamic State.

Johnson says radio bombs are in Martin Place, Circular Quay and George Street, which later proves to be false.

Johnson tells the operator he has a gun pointed at him, Monis has taken him and others hostage.

The call lasts 12 minutes.

9.46am: Police acknowledge the incident

9.51am: Police arrive at the scene.

9:52am: Tactical operations unit acknowledges the emergency.

10.07am: Tactical operations unit arrives

Siege is treated as a possible terrorist attack.

Monis had told his 18 hostages he has a bomb in his backpack, which he holds on to throughout the siege.

Mid-afternoon:

Some of the hostages escape

Monis fires his gun, striking the wall above the cafe door

DECEMBER 16

Very early AM: Monis fires his gun, striking the wall above the cafe door

2.14 am: Monis forces Johnson to kneel on the floor of the cafe and shoots him in the head. Johnson dies.

Shooting witnessed by police marksman who calls it in.

Police force entry to the cafe, shattering the glass windows and doors

Tactical units throw 11 flashbang grenades, creating sudden violent flashes of light and gunshot sounds

Two police officers fire 22 shots at Monis.

Monis returns fire, shooting shotgun once or twice at the entry team.

Monis is killed by at least two bullets or fragments to the head and 11 other bullets or fragments to the body.

Hostage Katrina Dawson is struck by six fragments of a police bullet or bullets, which ricochet from hard surfaces into her body.

One fragment strikes a major blood vessel. She loses consciousness and dies.

Three other hostages and one tactical operative are hit by ricocheting bullet fragments.

Source: Opening statement by counsel assisting the NSW Coroner Jeremy Gormly to inquest