Anne Stevens, counsel for Livingstone's estranged wife Katharine Webb, said the evidence to date painted a picture of Livingstone "deliberately deceiving" healthcare professionals.
Dr David Chaplow said it appeared Livingstone was weighing up his options in the days leading up to the killings.
Livingstone spoke to his new partner, Karen Wright, while drinking on a park bench little more than an hour before he shot his children with a 12-gauge shotgun, Dr Chaplow said.
Dr Chaplow said it appeared Livingstone was "hedging his bets" for some time before the killings.
Despite a number of "red flags" the slayings were ultimately unavoidable, Dr Chaplow said.
Robin Bates, QC, counsel for the 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.
"Some saw him as self-serving, others as deceptive, others as an alcohol abuser, others as narcissistic, but others as ... a loving father."
His one-time flatmate, Philip Mans, said he felt Livingstone "played" him to gain access to the firearm used to kill his children.
Livingstone stole the Stoeger shotgun from Mr Mans' firearms cabinet using a key he had stolen at an earlier date, the court was told this week.
Yesterday the court was told that the Department of Corrections, Livingstone's employer, was aware of his diagnosis of narcissistic personality disorder, that he often smelt of alcohol, he often appeared dishevelled, presented real risks, gave bullet casings to his children and had breached his protection order twice.
Despite this the department did not dismiss him, Mark Godwin of Corrections said.
The department did not know he had convictions in Australia or had raped Ms Webb.
