Mohammad Kiad and Omar Al Kutabi.

Mohammad Kiad and Omar Al Kutabi. Photo: Facebook

Six months ago, Omar Al-Kutobi told his father something deeply concerning.

The western Sydney nursing student, who was arrested on Tuesday allegedly just hours before carrying out an Islamic State-inspired killing, said he wanted to go back to Iraq despite fleeing with his family a decade earlier.

His desire to travel to the epicentre of Islamic State's terror campaign was the first sign that his psyche had changed, his father, Ahmad, revealed to The Sun-Herald.

Before then, he was a happy IT student who wanted to serve in the Australian army and said his citizenship ceremony in 2013 was one of the highlights of his life.

"From six or seven months ago, he started to change, I don't know," Ahmad said. "He ask me to go back to Iraq and I told him, 'No, they will kill you'. He said he wanted to see his mother. We had many fights on the phone about that. My son, he is not like that."

The concerns from Mr Kutobi's father were reiterated by those who lived next to the Fairfield granny flat that counterterrorism police stormed on Tuesday afternoon.

Police revealed in a media conference that officers seized a hunting knife, machete, home-made Islamic State flag and video allegedly filmed by Mohammad Kiad, 25, showing his flatmate Mr Kutobi holding both knives and vowing to strike the kidneys and necks of white people "today".

On Friday, police revealed they travelled overseas on Tuesday night and uncovered further information about the pair.

They allege the men had plotted to attack several other targets on Australian soil, including police and a prayer hall in Sydney.

The Sun-Herald understands they attempted to attack the prayer hall but it failed, for unknown reasons.

It appeared Mr Kutobi and Mr Kiad, both refugees, grew agitated and more devout just in the last six months, neighbours said.

They were glued to their television during the Lindt Cafe siege and changed their appearance in the weeks after, trading Nike sneakers and Dolce & Gabbana jeans for religious robes and beards.

Kiad, who worked as a nurse in Kuwait, began obsessively posting messages from a fan page for Egyptian sheikh Abdul-Hamid Kishk.

Oddly, the little-known sheikh died in 1996 and was better known in the '70s as a progressive and humorous leader. Relentless posts on the fan page were more about overthrowing the Egyptian regime than joining Islamic State.

Soon after getting a spousal visa in 2013, Mr Kiad separated from his wife and moved in with one of his few friends.

Like any normal young men, they enjoyed going to the gym, having barbecues with friends and working together as removalists.

But Mr Kutobi told his father, who lives in Germany, that he felt alone in Australia and was struggling with work and study. He was let go from work a week ago. He wouldn't say where his friend Mr Kiad was from.

"I don't know, I was having some feeling about him," he said. "Omar was so happy before. One day I told him, 'Who is that? I don't like him.' He was angry and said, 'Don't talk about my friends.'"

However, Mr Kiad's estranged wife told Channel 10 he was a romantic man who came to Australia full of hope to become a doctor and buy a house.

It appears the men had little influence from outsiders.

Counterterrorism police sourcessaid they knew next to nothing about the pair because they were forced to act so quickly on Tuesday, just an hour after the hunting knife was allegedly bought at a Smithfield military store.

It was a reflection of the new terror threat Australia faces; rapidly radicalised lone wolves who are almost impossible to detect until the 11th hour – and usually only after a public tip-off.

"This is indicative of the threat we now have to live with," NSW Deputy Commissioner Catherine Burn said.