At the first day of the inquest into the deaths of Livingstone and his two children, Bradley (9) and Ellen (6) Livingstone, Chief Coroner Judge Deborah Marshall heard police were trained not to grant diversion to offenders who had breached protection orders.
Livingstone shot Bradley and Ellen in their beds on January 15, 2014, in the St Leonards home the children shared with their mother.
It appears he then turned the gun on himself in the bedroom he formerly shared with his estranged wife, the children's mother, Katharine Webb.
The court heard Livingstone had twice breached a court-ordered protection order preventing him from contacting Ms Webb.
The order was first issued on May 5, 2013, and Livingstone breached it in August 2013 by contacting Ms Webb.
He admitted the charge and, as it was his first offence, was granted police diversion.
Prosecutor Sergeant Kate Saxton, during questioning by Judge Marshall, conceded that was a mistake.
''My understanding from training in diversion is that diversion isn't available for offences involving breaching a court order,'' she said.
Sgt Saxton was the police prosecutor who handled Livingstone's second breach of the order on September 14, 2013.
Police opposed the defence's submission for a discharge without conviction in that case.
Livingstone was granted a discharge without conviction on November 15, 2013, by district court Judge Stephen Coyle.
At the time, Judge Coyle believed Livingstone had no previous convictions. However, police were aware Livingstone had some history of offending in Australia, Sgt Saxton said.
''Although we didn't have specifics, we were aware there was a criminal history in Australia,'' she said.
The extent of that offending was revealed on December 9 when Sgt Saxton received notification from Interpol that Livingstone had been convicted of two charges - one of setting fire to a dwelling house and one of assault, in Australia in 1988.
Judge Marshall asked Sgt Saxton why an adjournment in court proceedings was not sought until all information was available to police.
''I felt that the information I had would not be acceptable to the court,'' she said.
The Dunedin District Court had heard the second breach of the protection order was minor in nature but a witness impact statement read out by Anne Stevens, counsel for Ms Webb, at yesterday's inquest conflicted with that assessment.
''I'm sure this will happen again tomorrow or the next day. I'm constantly harassed. I'm no longer the calm and confident person I used to be. I cry in public,'' Ms Webb's witness impact statement said.
Ms Stevens asked Sgt Saxton if that was reflective of a minor breach.
''No - it had a very serious impact on her,'' Sgt Saxton said.
Earlier, Dr Christopher Wisely, Livingstone's psychiatrist, detailed to the court his clinical contact with Livingstone.
Livingstone had deceived him during that time, Dr Wisely conceded when questioned by Mrs Stevens.
Dr Wisely was unaware of Livingstone's earlier convictions in Australia, or that he had presented bullet casings to his children as a present.
Those factors were relevant to his treatment and the ensuing deaths, Dr Wisely said.
Livingstone had convinced Dr Wisely he was ''managing as best he could considering the circumstances''.
''He did not harbour antipathy towards Katharine at all and that seemed to make sense to me because I couldn't understand why he would; she seemed to be entirely the victim in this,'' he said.
Livingstone had told Dr Wisely he suffered an abusive upbringing at the hands of his father and was abandoned by his mother when he was 3. He had also suffered two episodes of sexual abuse.
However, Dr Wisely said there was nothing he had heard or seen to suggest the tragedy that would unfold.
Former friends and acquaintances of Livingstone told the court he had spoken of his desire to kill his children and estranged partner months before he took Bradley and Ellen's lives.
Jeffrey Fleming, the husband of a co-worker of Livingstone's, told the court Livingstone had stated his intention to kill Bradley and Ellen shortly after Mr Fleming and Livingstone first met in mid-2013.
''The first method was stabbing them with a knife; he told me that he was thinking about that,'' Mr Fleming told the court.
''Then after that, he said another method would be shooting them.''
Livingstone briefly lived with Mr Fleming and his wife.
Livingstone moved out of the Kiwi St home he shared with his estranged wife, Ms Webb, after the relationship completely broke down in May 2013.
The coroner's court heard how Ms Webb separated from Livingstone after he raped her.
Ms Webb told police about the rape but did not want to pursue charges.
''That wasn't my focus ... my main focus was the safety of the children and just to get away from him,'' she said.
Livingstone also outlined to his former neighbour, Melanie Foot, his plans to kill the children and Ms Webb.
He briefly lived with Mrs Foot and her husband, Christopher, after leaving the family home.
Livingstone told Mrs Foot he would kill the children and Ms Webb with the back of an axe before taking an overdose of sleeping pills, Mrs Foot told the court.
He planned to gather the family together into bed before setting fire to the family home.
She passed the information on to police but they did not take it seriously or treat it as a threat, as it was hearsay, she said.
Robin Bates QC, counsel for police, questioned whether Mrs Foot had called police about the threat and passed the information on.
''I don't know the date that I talked to police, whether it was the 8th [of August] or earlier or later, but I definitely made the call,'' Mrs Foot said.
Erin Kealey, a Corrections officer and co-worker of Livingstone, detailed changes to Livingstone's personality.
His manner had changed in early 2013 and, after his separation from Ms Webb, he experienced ''dramatic weight loss'', she said.
''He would shake all the time; he was on medication, which he felt was contributing to what he was feeling.''
Issues, such as the death of his dog, left him unable to cope emotionally, she said.
Many of the witnesses spoke about how Livingstone blamed his actions and thoughts on antidepressant and smoking cessation drug Zyban.
Earlier, the court heard how Livingstone had presented bullet casings to his children as a gift in the months before the killings.
Ms Webb said she felt it was a message to her and it frightened her to know Livingstone had access to firearms.
She also believed Livingstone might have slashed her car's tyre.
Those incidents were outlined during Ms Webb's emotional and harrowing testimony.
Ms Webb detailed how Livingstone had cancelled her house and car insurance and contacted a real estate agent to put the house on the market - all without consulting her.
At times, Ms Webb choked back tears.
Mr Foot told the court Mr Livingstone had sent him a text message hours before the killings, saying ''look after yourself karma will get Kath''.
Mr Foot confronted Mr Livingstone as the shooting unfolded and was himself fired at.
Judge Marshall said Mr Foot was an ''extremely brave man'' for putting the children's safety before his own that night.
The hearing is set down to conclude on Friday.
