A Victorian detective says there was no "real perceived urgency" to arrest Greg Anderson in the days before he murdered his son.
Detective Senior Constable Andrew Cocking said Luke's mother, Rosie Batty, had given him Anderson's latest address two days before the 54-year-old killed Luke Batty.
But she asked the detective not to make it obvious she had given the information to police.
Det Sen Const Cocking told the inquest into Luke's death on Friday he feared Anderson would have "put two and two together" if he arrested him immediately after speaking to Ms Batty.
"There was no real perceived urgency in this matter," he said.
"It's important to do jobs right and not in a rushed manner, especially this one."
Anderson murdered Luke, 11, with a cricket bat and knife as they played together after cricket training at Tyabb oval on February 12.
At the time, Anderson faced multiple warrants for his arrest, child pornography charges and was the subject of an intervention order after threatening to behead a house mate.
Det Sen Const Cocking said had Anderson been arrested before he attacked Luke, he would have opposed Anderson's bail application.
But he said he believed a magistrate would have granted Anderson bail anyway.
"The starting point is bail," Det Sen Const Cocking said.
Ms Batty had earlier told the inquest she gave Anderson's address to the detective about February 5.
He had charged Anderson for accessing child pornography in a public library in January 2013, but because Luke was not the subject of the material, he did not believe he needed to warn Ms Batty.
Under those circumstances, Det Sen Const Cocking said he felt telling Ms Batty about Anderson's behaviour would have been counterproductive.
"Those charges are very emotive," he said.
"That information, once it's in the public domain, would do more harm than good."
Ms Batty had earlier told the inquest she had learnt the basic details of the child porn charges from another police officer and feared Luke was being groomed by his father.
Social workers later approached Det Sen Const Cocking to learn more details of Anderson's offending and reassured Ms Batty Luke was not the target.
The inquest continues.
