"What we know from the lady friend [Ms Wright] is by half past 8 [pm on January 15, 2014] he was sitting in a park feeling quite morose and thinking about what he's going to do," he said.
It appeared Livingstone was "hedging his bets" for sometime before the killings.
"It seemed to me he had been thinking about his options, so to speak, for a day or two -- hence stealing the gun, stealing they key," Dr Chaplow said.
Livingstone stole the Stoeger shotgun used in the shooting from his one-time flatmate Philip Mans.
Livingstone stole the gun from Mr Mans' firearms cabinet using a key to Mr Mans' Milton house which was stolen at an earlier date, the court heard yesterday.
Despite a number of "red flags" coming to the attention of the clinicians dealing with Livingstone, the slayings were ultimately unavoidable, Dr Chaplow said earlier today.
Robin Bates QC, counsel for police, asked "if somebody makes up their mind to do this sort of thing, there's a high likelihood they will do this despite all the interventions, is that a correct comment?".
"That is a correct comment," Dr Chaplow said.
Livingstone seemed to "impression manage" his clinicians, not allowing them to gain a full insight to his personality.
"Different people had their own snapshots of those personality characteristics," he said.
"Some saw him as self-serving, others as deceptive, others as an alcohol abuser, others as narcissistic, but others as... a loving father," he said.
Livingstone's duplicity became apparent during day one of the inquest when the court heard he had deceived his psychiatrist Dr Christopher Wisely.
A co-worker told the court on Tuesday she felt Livingstone knew "what to say to the right people to get them off his back".
This morning the court also heard that the Department of Corrections, Livingstone's employer, were aware of his diagnosis of narcissistic personality disorder, that he often smelt of alcohol at work, he often appeared dishevelled, he presented real risks, gave bullet casings to his children as a gift and had breached his protection order twice.
Despite this Corrections did not dismiss him from employment, Mark Godwin, of Corrections, said.
Corrections did not know Livingstone had convictions in Australia or had raped Ms Webb.
Livingstone was convicted of arson and assault in Australia in 1988.
In May 2013, Livingstone trapped Ms Webb in their bedroom and brutally raped her over a period of five hours, even as their distraught daughter banged on the door.
Police were made aware of that information when they attended an incident at the residence on May 27, 2013.
Ms Webb sought a protection order and it was first issued on May 31, 2013, and finalised on August 13.
On August 7, 2013, Livingstone breached the order for the first time.
While reporting the matter to police, Ms Webb presented a number of empty bullet cartridges which Livingstone had given to Bradley and Ellen during an earlier supervised visit.
Police disposed of the cartridges and did not take the matter further.
Mr Mans, the owner of the shotgun used in the shooting, is expected to give evidence later today.
The court also heard Livingstone's depression was "atypical" and his happiness tied to the hope of reconciling with his estranged wife
Dr Chaplow said Livingstone's depression was not biological and his responsiveness to medication was too convenient.
The inquest is now in its third day.
