Coronial inquest into Sydney cafe siege opens

The gunman and 2 hostages were killed after police stormed the cafe, ending the 17-hour long hostage drama

The coronial inquest into the Sydney's Martin Place siege, in which more than a dozen people were taken hostages by a self-styled cleric, formally opened here this morning.

The inquest, which will be conducted across sessions throughout the year, will examine the circumstances and issues that led to the deaths of Tori Johnson, Katrina Dawson and the gunman Man Haron Monis at the Lindt Cafe in Martin Place in a siege that began on December 15 last year.

According to media reports, it would also probe the background of Monis, a self-styled Islamic cleric, to understand if he was an ISIS-inspired terrorist or a "deranged individual" seeking to deal with a private grievance in the most public way possible.

Coroner Michael Barnes said the first tranche of evidence would revolve on Monis, who, during the siege, took more than a dozen people hostage in the cafe.

Police and hostages will be among those to take the stand during the course of the inquest, according to reports.

Monis's partner Amirah Droudis, who is in custody, had legal representation at a preliminary hearing but it is not known if she will be called to give evidence.

At that hearing, counsel assisting the coroner Jeremy Gormly SC said an investigation into Monis's background would cover issues including "his political activity, his religious claims, his criminal history, his record of public activity, his media profile, his litigation history and his personal and family relationships," ABC said.

The inquest will also examine the way authorities responded to the siege and the events that took place in its aftermath.

The gunman and two hostages were killed and four other people injured after police stormed the cafe, ending the 17-hour long hostage drama.