John Edwards, the man who shot his two children dead last Thursday, was able to pursue his handgun training because he was granted a so-called “Commissioner’s Permit", overriding red flags raised by his answers on declarations about his background.

It is understood this permit reassured officials at the St Mary’s Indoor Shooting Centre that Edwards could legally undergo handgun training - the first step towards getting a handgun licence and then a permit in NSW - despite his answers on a declaration form raising flags in the system.

John Edwards shot dead his children Jennifer and Jack before taking his own life.

"With a history like his, there is no way he ever should have been given the Commissioner’s Permit," Shooters, Fishers and Farmers Party MP Robert Borsak said. "Whoever did it, whoever it was who did the double check and the triple check on [Edwards] somehow failed on this occasion."

Edwards killed his son Jack, 15, and daughter Jennifer, 13, in West Pennant Hills before later turning the murder weapon on himself in his Normanhurst home.