But on Friday, this quiet boy from Sydney’s west changed into black flowing robes and executed a NSW police employee outside the force’s Parramatta headquarters during his school holidays.

Muslim community leaders are grappling with how to prevent young people such as Jabar being drawn to the cult of violent extremism. Last year, 18-year-old Numan Haider was shot dead after attacking two counter-terrorism officers with a knife outside the Endeavour Hills police station in Melbourne’s southeast. In May, police arrested a 17-year-old boy in Melbourne’s north believed to have been plotting a Mother’s Day massacre, finding three pipe bombs in his bedroom. And in Britain, a 15-year-old boy was last week sentenced to life in prison for plotting an Anzac Day parade massacre in Melbourne.

Islamic Council of Victoria secretary Kuranda Seyit says parents are often the last to know that their children are plotting such heinous crimes. He says he has spoken to several distressed parents who have become aware of their children’s radicalisation only after a knock on the door from security officers or after their teenagers have already bought a ticket to fight in foreign conflict zones.

“The parents are absolutely gobsmacked when they find out,” he says. “Initially they are in a sense of denial that their child could be thinking about doing something like this and they’re confused about how their young child went down this pathway.”

There is a suggestion Jabar’s family had links to a Sydney man charged with recruiting others to join the fight in Syria, and his sister is feared to have travelled to join that conflict. However, Seyit says the parents he has spoken to have been just “normal Muslims”. He says there has been little in place to help them recognise when their children are becoming radicalised or to support them when they do.

“The Muslim community across Australia is really finding itself in a bind,” he says. “It really wants to support the government but the reality is neither the government nor the security agencies, or the Muslim community, understands how to tackle this problem … We are behind the eight ball.”

Seyit believes the government has been too slow to invest in prevention. He wants to be able to offer counselling and mentoring to young people at risk, as well as support for parents.

The government says it has tripled funding for programs to counter violent extremism from $3 million a year to $40m over four years. Some of this funding has been awarded to community-based organisations to develop the skills to help individuals turn away from violent ideologies.

Sydney Muslim community leader Jamal Rifi agrees with Seyit that parents can do more to detect when children are being radicalised and to seek help from others.

“The best way to be able to do this is the mums and dads,” he says.

“That’s the missing link and this is what we were shouting from the roofs.”

On Saturday night, Rifi was part of a teleconference with Malcolm Turnbull, NSW Premier Mike Baird and others to discuss deradicalisation and how the government can engage with the Muslim community.

Rifi says there’s been a dramatic — and positive — change in the federal government’s approach. He says previously the government and the Muslim community were “pulling in opposite directions” and the government was not working with the community to prevent radicalisation of young people.

“Right now, the message is different,” he says. “The Prime Minister and the Premier, they listened. It has never happened before, not with any other prime minister. It was more about engaging and being in a real partnership ... It’s about getting the Muslim community to play a role and we want to play a role.”

National security experts want the government to do more to prevent young people from becoming engaged with violent extremism — but don’t necessarily think this should be put on to Muslim organisations or mums and dads.

One security source wants the approach to be much more closely targeted at those individuals already linked to known terrorists, because it is those people who are most at risk of going on to plot other attacks.

He says the government has failed until now to put in place any sort of intervention aimed at ­diverting those individuals from violence, using counsellors, psychologists or other experts.

Only in the most recent budget, he says, did the government set aside $11.5m over four years for this sort of intervention, pointing out this was dwarfed by its investment of $640m for prosecution and intelligence and $545m for multicultural or social cohesion programs.

The source says while the Muslim community must be part of any overall strategy, such targeted intervention must be led by police.

“For such high-risk areas as this, while the community thinks quite rightly that it can help in this area, we are talking about individuals who kill people ... you can’t have an intervention that is not police-led,” he says. “They (the police) can co-ordinate with ASIO and law enforcement and actually know all the background information that the community is never going to know.”

However, Islamic State has developed a slick social media strategy aimed at recruiting young, often disaffected individuals to its cause and inciting them to violence. Monash University counterterrorism expert Greg Barton says the group deliberately targets anyone online who expresses an interest in the organisation and invests time in winning their confidence.

“It’s cunning and effective, particularly when it involves very young people,” he says.

“In some cases it is true we know of a level of risk because we know of family connections. But in other cases there is simply no warning, it just happens to be a random thing — someone wanders on to an online discussion, asks a question … and a relationship builds from there.”

Barton says the government must get better at systematically following up with every young person stopped at an airport or diverted from possible terrorist activity, and to ensure experts and community members work with them to lead them on to a healthier path.

He also believes the general community should be educated to look for warning signs of radicalisation. He says the alleged Melbourne Mother’s Day massacre plot was only prevented because of the “gutsy” decision of one of the boy’s friends to contact a security hotline after he became concerned about his social media posts.

Curtin University associate professor Anne Aly, an expert in counter-terrorism, says the 15-year-olds of today were born at the time of the 9/11 terror attacks and have grown up with the rhetoric of the “war on terror”.

She says that attack was a missed opportunity to teach young people about the harms of violence and to empathise with its victims. She believes schools should help to prevent the problem in subtle ways, for example by teaching students how to resolve conflict in nonviolent ways and to understand the consequences of violence. Even eight-year-olds can be taught that and benefit from those lessons.

She also thinks parents should be braver at discussing issues such as the conflict in the Middle East with their children.

Barton says while the government was recently criticised for some clumsily chosen examples in its anti-radicalisation kit distributed to schools last month, it is a good idea to help teachers, parents and others recognise someone whose wellbeing is at risk.

Like other initiatives, he says, “it’s hard to get it absolutely right but its absolutely vital that we keep trying”.