Australian police stormed a cafe Monday where an apparent Iranian refugee held people at gunpoint and forced them to display an Islamic flag. It’s an unsettling reminder of extremism, and the man said to be behind it has a long history of threatening and insulting the grieving families of fallen Australian soldiers.

Man Haron Monis was identified by multiple media outlets as the man behind the attack. Also known as Sheik Haron, he was convicted in September 2013 of sending “grossly offensive” letters to the families of fallen Australian soldiers, according to an Australian news report at that time. He is not considered a legitimate cleric by the Supreme Islamic Shia Council of Australia, according to a report in the Globe and Mail.

Monis pleaded guilty to 12 counts of using the Australian postal service to cause offense. But he provided no apology, saying his letters were “flowers of advice.” Had he delivered the letters in person, he said, he wouldn’t have broken any laws. He called the soldiers murderers and said they were going to hell.

“Always, I stand behind my beliefs,” he told reporters at the time.

A report in Monday’s Herald Sun newspaper of Melbourne said Monis arrived from Iran in 1996. Earlier this year, he was charged with sexual assault, and he was on bail after being charged as an accessory to murder in the death of his  ex-wife, the newspaper said. She was stabbed 18 times and set on fire, the Globe and Mail reported.

Monis said Monday that he was acting on behalf of the Islamic State militant group that has swept across Syria and Iraq in a wave of violence and prompted a military response from the United States and partner nations, according to several media reports. But it’s unclear whether that is the case.

In addition to his letter writing, Monis has a history of making bizarre statements. In 2009, he even made an appeal to The Wiggles, a children’s music group, to make a video for orphans who have lost their parents in war.

“The Wiggles love kids much more than some politicians,” Monis said at the time, according to the Daily Telegraph of Sydney. “I want to ask The Wiggles to make a special show for Iraqi, Afghani and Australian kids that have lost their parents in war.”