The parents of Australian teenager Adam Dahman are still reeling that their son is dead - a suicide bomber who killed five civilians in a marketplace in Iraq.

Described by neighbours in the Melbourne suburbs as a "normal kid", the baby-faced 18-year-old wore a bomb belt on July 17 and blew himself up for ISIS.

Go to Dahman's Facebook page and just two clicks connect you to a group of young Perth men who similarly hold up their index fingers while posing with Islamic State flags and paraphernalia.

One of 12 Facebook users to "like" Dahman's last profile picture before his death was "Abu Hamza", a Melbourne-based Facebook friend of Mohammed Junaid Thorne.

Another of the 12 was "friends" with a page carrying a picture of Thorne's brother Shayden.

Asked on Friday what he knew about Dahman and the Abu Hamza page (the operator's real name is probably something else - Abu Hamza is a name often taken by terrorists), Junaid Thorne would only respond: "I don't know them."

On Saturday, _The Weekend West _revealed that a small group of young Perth men were causing deep concerns in the Muslim community that they were becoming radicalised supporters of the IS movement.

WA imams have denounced the ideological base of lectures and pronouncements by Junaid Thorne, 25, who grew up with his brother in Saudi Arabia.

He returned to Perth last year after being deported and his brother returned this year, having spent several years in a Saudi jail on terrorism-related charges.

Analysis of social media links between the Perth-born brothers and their connections exposes a virtual labyrinth of young male enthusiasts devoted to hardline Islamic doctrine and jihadist ambitions in the Eastern States and overseas.

No one knows how far any of them are from acting on the rhetoric, as Dahman did.

It has been reported that Dahman was "brainwashed" when his sister married into Melbourne's notorious Raad family, which had two members jailed for their role in a home-grown terrorist cell.

Former school friends of Dahman have said he suddenly became more devout in 2012.

Curtin University terrorism expert Anne Aly, who chairs the national People Against Violent Extremism Organisation, said Perth families needed help to draw their sons away from cult-like thinking.

Dr Aly has approached the Federal Government to fund a de-radicalisation program - being rolled out in Germany, Canada, the Netherlands and Britain - in Australia to intervene before more Australians are killed.

She said the Hayat method was a family counselling program done in conjunction with police and security agencies.

"The problem for law enforcement is that they often can't get involved until that pointy end," Dr Aly said.

"They'll watch and watch as a young person gets more radicalised but they can't intervene until they are planning violence.

"The radicalisation process is usually quite slow to begin with and they often don't realise they are becoming radicalised. Then the last part of that process from when they accept violence to actually carrying out a violent act is quite rapid and it has to be rapid so they don't pull out at the last minute or have doubts at the last minute.

"It's during that slow process, which could take years, from when they first start seeking the information to when they become actually actively engaged in it, writing and posting things online - that level there is the best time to interrupt, to get in and pull them out of that."

Dr Aly, who has had personal experience with several of the Perth men associated with Thorne's Millatu-Ibrahim group, said they needed help to realise that what they believed was more a cult than a religion.