He said the centre of focus was on ensuring no more lives were lost, and that included the life of the gunman.
"The one thing above all you need to possess in situations like that is empathy," Burdett said.
"To understand the situation they are in - it is to put yourself in their position and say 'I'm walking with you'."
Burdett said police had allowed "controlled" communication between Molenaar who, at the end of the first day of the siege was showing signs of tiredness, and his partner Delwyn Keef.
Molenaar had told Burdett that he did not want to hurt any more officers.
There was communication with Molenaar upon the hour. Burdett wanted to allow Molenaar to rest for a time, to freshen his mind a little and then try and go from there.
On the second day, he sensed Molenaar was intending to take his life, or make a move that would end up effectively as "suicide by cop".
Burdett said although Molenaar continued to fire shots from the house and would explode into bursts of rage and begin "ranting", there were also the moments when he would quieten down and there would be sorrow in his voice.
Burdett said he sensed how it was all going to end.
In hindsight, he thought about what else could have been done, of whether there should have been a different approach. But he accepted that at the time there was not.
"There was probably one more strategy, although we were not aware of it at that time - but I can't disclose it."He and his colleagues wanted to take Molenaar alive and there was a touch of self-questioning about how it had been handled."
But one of the tactical guys came up, saw I was struggling with it a bit, and said 'if we had tried to go through that door there would have been three more cops shot'."
The negotiating role, along with other stressful slices of senior police work, took a toll on Burdett and the book, with no holds barred, outlays the pressure of it all.
He sought and took mental health assistance when it all became overwhelming and burn-out edged into inevitable depression.
Nightmare situations resulted in nightmares. Writing the book, he said, was "tough going" because everything came back.
There were highly charged, emotional situations during the siege that he still cannot talk about without tears. Even though he went through it all on the frontline he still finds it tough to read or relate.
"These things never go away."