Melbourne - The Australian man who killed his 11-year-old son at cricket practice should have been arrested weeks ago, police admitted on Friday, revealing there were five warrants out for him.
Luke Batty was beaten to death, reportedly with a cricket bat to the head, in front of stunned onlookers after training with his junior team on Wednesday evening at Tyabb oval, 100km southeast of Melbourne.
Police arrived to find his mentally ill father Greg, aged 54, armed with a knife. He was shot once in the chest and died in hospital.
Victoria state police chief commissioner Ken Lay said Anderson had been questioned about assault allegations on 27 January, but officers had not been aware that he already had five outstanding arrest warrants against him, for failure to attend court.
He blamed an antiquated computer database for the oversight, but said it was only one piece of a complicated case.
"This is not me blaming an IT system for the death of a young boy," he said.
"It is one part of a very complex issue for us."
The father was estranged from his wife and had a history of mental illness.
He was the subject of an apprehended violence order (AVO), which was taken out by the boy's mother Rosie according to media reports, but it allowed him to visit the boy at his cricket training.
An AVO is taken out by someone if they fear for their safety, and prohibits harassing, threatening and intimidating behaviour by the subject.
"The worst thing that could have ever happened to me has just happened," the boy's devastated mother Rosie, who was at the scene when the killings took place, told Triple M radio.
"And a little boy, who was innocent, because of a selfish act from his father who wanted to die [and] wanted to take him with him."
Lay said investigations were underway into how police handled the case.
"These investigations will look not only into the events of the night but all the relevant circumstances and response of a whole history of interaction with Luke, Rosie and their family," he said.
"Hopefully it will be a watershed in improving the way we respond to these issues, for not only Victoria Police but the broader community."