The gunman killed along with two of his hostages at the end of a 16-hour standoff in a Sydney chocolate cafe had been charged as an accessory in his ex-wife's murder in 2013 and was out on bail.

Man Haron Monis' former wife was found dead in an apartment stairwell in April last year. Noleen Hayson Pal, 31, was stabbed repeatedly and burned alive in the stairwell.

Like Us on Facebook

Charged with murder seven months later was Monis' girlfriend, Amirah Droudis, while he was charged as an accessory. They were released on bail.

"They should have put him away and thrown away the key," said Pal's godfather Ayyut Khalik.

Khalik said he disliked the Iranian-born Monis the first time they met. He would find out later that Monis had been hurting Pal. He was also telling his children that white people are bad, Khalik continued.

Khalik said the self-styled sheik would force Pal to wear the hijab at all times and limit her social contact to just fellow Muslims. Monis and Pal had two sons.

Authorities claim that Monis, who called himself "the brother" in dealing with the police and the media during the hostage-taking, had been in the police radar for a long time because of his lengthy criminal record.

In a news conference, Prime Minister Tony Abbott said Monis' long criminal history included violent crimes, obsession with extremism and even mental instability.

Aside from his ex-wife's murder, Monis was allegedly involved, among others, in the sexual assault of a woman in Sydney in 2002 and six other sex-related charges after pretending to be a faith healer in order to grope victims.

Monis, also known as Sheik Haron, gained notoriety when he sent hate-filled emails to the families of Australian troops killed in Afghanistan. He was convicted and sentenced to 300 hours of community service.

Tagssheikh haron, chocolate cafe, Sydney Hostage, Man Haron Monis, ex-wife murder