The Sydney siege gunman’s bizarre and troubling behaviour in the years leading to his death appeared to have been sparked by a program aired by the Seven Network, leading to speculation his intended target was the broadcaster’s Martin Place studios.

The revelations come amid reports Man Haron Monis may have been spooked by heavy security at the TV network’s offices on Monday morning and decided instead to take 18 people hostage in the nearby Lindt Chocolate cafe, in a siege that ended with the death of the gunman and two of his captives.

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Monis’s former lawyer Manny Conditsis says the self-proclaimed sheik had in July, 2007 been angered by what he saw as anti-Muslim comments on the Sunrise program.

The popular breakfast show was covering the arrest of Indian doctor Mohamed Haneef in Australia following the failed terrorist attacks in London and Glasgow.

Monis felt a commentator on the program was drawing offensive links between Dr Haneef, who was later cleared of any links to terrorism, and the Glasgow bomber who was also a Muslim doctor.

“Attention please attention, a ridiculous message for Muslim doctors: If you want to kill people, why not use the tools of your own trade like a plague or a disease or something? Why go into an area which you’re clearly unqualified in?” (Sunrise broadcast 4th July 2007, Australian TV, Channel 7),” Monis posted on his website at the time.

Monis made many more references to Sunrise and the Seven Network throughout his site, which has since been taken down.

“Channel Seven’s broadcast on 4th July 2007 changed my life!” Monis wrote in bold letters on one link.

Mr Conditsis said the program left a deep mark on his client, with Monis saying it pushed him to send several letters to the Seven Network, politicians and the broadcasting watchdog.

“A lot of things were said that (Monis) took offence to,” Mr Conditsis told AAP.

“It all developed from there, his perception that everyone in the whole world, and particularly the Sunrise program, were anti-Muslims.”

In one of Monis’s rambling letters, he accused Sunrise of “instructing terrorism” by suggesting Muslim doctors could hurt more people in their own profession rather than turning to terrorism.

In the months after the program, Monis’s behaviour would become increasingly erratic, as he turned his attention to penning offensive letters to the families of dead Australian soldiers.

Mr Conditsis said Monis was “blinded by his cause” and totally focused on the perceived injustices he was experiencing.

“You’d talk to him, you’d think he’s listening, nodding his head and then a minute later he’s back on exactly the same stuff,” the lawyer said.

But he insisted despite Monis’s behaviour and online posts, it would have been impossible to predict that he would become a hostage-taker, especially given he had no history of proven violence.

Comment has been sought from the Seven Network.