Cowardly dad who killed his two children before turning the gun on himself kept a machete under his bed and repeatedly threatened to kill his ex 'for taking his kids away from him'

The cowardly dad who brutally murdered his two teenage children also threatened to kill his ex-partner and kept a machete under his bed, an inquest heard.

John Edwards shot dead his son Jack, 15, and daughter Jennifer, 13, on July 5, 2018, before turning the gun on himself at his northern Sydney home following the break-up of his marriage. 

His ex-wife and the mother of their children Olga Edwards would later kill herself because she was so consumed by grief. 

An inquest heard on Thursday how Olga repeatedly told her barrister Peter Fowler that her husband would make yearly threats to kill an ex-partner who 'took the children away' from him.

Olga had stated Edwards would mark the anniversary of the 2002 death of an estranged child by making verbal threats to kill the child's mother, Mr Fowler said.

'That's something Olga heard once a year throughout the relationship. That bore on her mind.' 

Edwards killed himself at his rented home near Normanhurst on the night of the murders

Olga fled the violent marriage and the family home with their two children and launched divorce proceedings in April 2016. 

But Mr Fowler told the inquest that a Family Court order made in December 2016 required the children to spend at least three hours per week with their father despite their strong wishes not to do so.

Both children were scared of their father as he had been physically violent towards them on previous occasions, the inquest heard.

Olga was eventually given sole custody of the children in February 2018 and a no contact order was levelled against Edwards.  

Edwards gave evidence to the Family Court at the time conceding that he kept a large machete under his bed, the inquest heard. 

Mr Fowler said that after the 2016 separation, Olga had significant fears Edwards was stalking her and the kids.

He turned up at her dawn yoga class, she once saw him driving past her house and one of his statements in family court proceedings indicated knowledge of Jennifer's route to school.

Edwards also arrived unexpectedly when Olga and Jennifer were selling cupcakes for charity at a shopping centre.

Jack (pictured left) and Jennifer's (pictured right) body were found under his bedroom desk with multiple gunshot wounds

She refused to disclose the family's new address during the divorce proceedings.

When a judge in June 2016 proposed to allow Edwards to know the family address if he stayed at least 500 metres away, Edwards declined.

'The fact he declined to agree to that concerned her,' Mr Fowler said.

Olga, who took her life five months after her children's murders in July 2018, was 'disappointed and surprised' in the police response to her reporting Edwards had stalked her and been violent to the children, Mr Fowler said.

The barrister had 'little doubt' Olga would have taken the children out of school and made moves to 'further secrete' the family's whereabouts had she known he had a gun licence.

Edwards, 67, turned the gun on himself at a rented home near Normanhurst, northern Sydney  

Edwards was granted the rifle and pistols licences in June 2017 after firearms registry staff failed to take note of adverse events on his police record.

He used his legally owned Glock pistol to murder Jack, 15, and Jennifer, 13, in their Sydney home before returning to his home and shooting himself.

The police superintendent parachuted into the position of registry commander after the July 2018 deaths told the inquest staff were now extensively trained on the criteria for granting licences and how to notice patterns of risk in domestic violence.

Superintendent Anthony Bell said when he arrived he found clerks and their supervisors were processing 300 licences weekly without properly determining if a person was 'fit and proper' as required by law.

'I found some were, but the majority didn't (carry it out) and they didn't have a true understanding of that component,' Supt Bell told the inquest on Thursday .

'They struggled because of the subjective nature (of the term).'

Asked how the registry had reached a state of failing a central aspect of its job - determining who was safe to get a gun licence - Supt Bell said it was a question for his predecessor, retired superintendent Bruce Lyons, and the former management.

'I identified it pretty early,' Supt Bell said.

'It's a concern. It was a red flag to me as a police officer. The whole way I go about it is 'What does the legislation say?''

He said staff had been instructed to escalate to senior adjudicators when unsure about whether to grant a licence.   

The inquest continues. 

If you or anyone you know is in need of mental health support, you can call Lifeline 13 11 14, or Beyond Blue 1300 22 4636. 

The shocking history of John Edwards before he gunned down his two youngest children in cold blood