Sydney Hostage Crisis
Photographs of Sydney's cafe siege victims, lawyer Katrina Dawson (L) and cafe manager Tori Johnson are displayed in a floral tribute near the site of the siege in Sydney's Martin Place, December 23, 2014.Reuters

Barrister and mother-of-three Katrina Dawson, 38, one of the victims of Sydney's Lindt Cafe terror siege last month died after she was struck by at least six fragments of police bullets that ricocheted as police stormed into the cafe to end the 17-hour hostage crisis.

Lindt cafe manager Tori Johnson was, however, killed in a chilling execution with Islamist gunman Man Haron Monis asking him to kneel before him and then shooting him in the back of his head, an inquest into the terror attack has revealed.

"Ms Dawson was struck by six fragments of a police bullet or bullets which ricocheted from hard surfaces into her body," counsel assisting the coronial inquest, Jeremy Gormly, said on Thursday.

One of the fragments reportedly struck Dawson in a major blood vessel, and she succumbed to her injuries soon after the 17-hour siege ended on 16 December.

Monis had reportedly warned the hostages that he had a bomb in his backpack, the inquest has revealed according to The Sydney Morning Herald.

Police stormed into the cafe after a sniper reportedly witnessed Monis shooting Johnson at about 2.14 am on 16 December.

The police reportedly used 11 SF9s "flash bangs" that triggered loud bangs and flashes of light creating an illusion of a hail of bullets.

Two of the snipers then fired at Monis with at least 22 rounds, and he was hit in the head by two bullet fragments.

The inquest will also scrutinise the police response and management of the situation, and Gormly said that it will also make criticism against the police if necessary.