Sydney hostage-taker called himself a cleric -- and had a criminal record

(CNN) -- Before he was killed in a Sydney cafe, the gunman who held hostages there for more than 16 hours was no stranger to police.

The hostage-taker was Man Haron Monis, an official with direct knowledge of the situation said Monday.

"He had a long history of violent crime, infatuation with extremism and mental instability," Australian Prime Minister Tony Abbott told reporters.

Australian media reports paint a harrowing picture of Monis, 50, detailing his lengthy criminal history.

The self-styled Muslim cleric, also known as Sheikh Haron, pleaded guilty last year to writing offensive letters to the families of Australian troops.

Firefight occurs during hostage crisis

Sydney gunman identified

Witness: Woman screamed, 'He has a gun'

That same year, he was charged with being an accessory to the murder of his ex-wife. Noleen Hayson Pal was found dead with multiple stab wounds in a stairwell, and her body had been set on fire, The Sydney Morning Herald reported.

"They should have put him away and thrown away the key," the dead woman's godfather, Ayyut Khalik, told NBC News. He said Monis used to beat Pal, forcing her to wear a hijab all the time and forbidding her from talking to "outsiders."

In April, sex crimes detectives arrested Monis and charged him with sexually assaulting a woman in western Sydney in 2002, according to The Sydney Morning Herald. Other sex-related charges were added regarding six additional victims, the newspaper said. Police reportedly said Monis was using the name Mohammad Hassan Manteghi and claimed to be a "healer."

Monis was out on bail, the reports said. He was sentenced to 300 hours of community service after sending letters to the families of Australian soldiers who died in Afghanistan. The letters were "sadistic, wantonly cruel and deeply wounding," one High Court judge said at the time, according to CNN affiliate Seven News.

And the criminal accusations against him began before he came to Australia.

Monis was born in Iran and fled the country in 1995 while being sought for allegedly committing fraud, Iran's semi-official Fars News reported.

An extremist theology

He used the Internet to spread extremist beliefs, garnering nearly 13,000 likes on his Facebook page.

"He posted graphic extremist material online," Abbott said.

And during the siege, Abbott said, the hostage-taker "sought to cloak his actions with the symbolism of the (ISIS) death cult," Abbott said.

In social media posts, Monis appears to embrace a radical Sunni extremist theology.

On his website, which has now been taken down, there was a pledge of allegiance to the so-called Islamic State terror group.

The site describes Monis as a Muslim cleric and activist based in Sydney who has "continuously been under attack & false accusation by the Australian government & media since he started his political letter campaign from 2007."

There's a graphic photo of slain children at the top of the site. Under the image, it reads, "This is an evidence for the terrorism of America and its allies including Australia. The result of their airstrikes."

A description on the site portrayed Monis as a victim of a political vendetta and compares him to Julian Assange, the WikiLeaks founder who has claimed the sex crime allegations he faces are politically motivated.

A YouTube video posted in November shows Monis standing on a street corner, chains draped over him, carrying a sign that says, "I have been tortured in prison for my political letters."

Police have refused to comment on that accusation.

His last tweet linked to his website, with a haunting message posted the day of his attack on the Sydney cafe: "If we stay silent towards the criminals we cannot have a peaceful society. The more you fight with crime, the more peaceful you are."

His former lawyer, Manny Conditsis, told Australian public broadcaster ABC that Monis was an isolated figure who was probably acting alone.

"His ideology is just so strong and so powerful that it clouds his vision for common sense and objectiveness," Conditsis said.

The ABC report said Monis had been granted political asylum in Australia.

The Australian government granted him asylum, Iran's Fars News said, despite Iranian police pursuing his return to Tehran through Interpol.

He was born Mohammed Hassan Manteghi and later changed his name, Iran's state-run IRNA news agency said.

Crisis in a cafe

Monday's hostage situation began around 10 a.m. Hundreds of police officers, including snipers, took position around the Lindt Chocolate Cafe in Sydney's central business district.

Australian media captured haunting images of hostages pressing their hands against the cafe's windows. They were reportedly taking turns holding a black flag with Arabic writing on it that said, "There is no God but God and Mohammed is the prophet of God."

The man holding the hostages demanded to speak to Abbott. Police were monitoring social media because hostages appeared to be posting information about the man's demands.

Hours into the crisis, at least five hostages managed to escape, running terrified toward police in riot gear. That made the hostage-taker furious, reported Chris Reason, a correspondent for CNN affiliate Seven Network. Reason said he could see the gunman become "extremely agitated" when he realized what had happened, and he "started screaming orders" at the remaining hostages.

Gunfire erupted early Tuesday as police stormed the cafe where the gunman had been holding hostages.

Two hostages were killed during the standoff. Police later announced that the siege was over and that the lone gunman had been killed.