Teachers at Bradyn Dillon's school made multiple reports to child protection about bruises on the boy's face, an inquest has heard.
But a senior teacher at the school told the ACT Coroner's Court on Tuesday that she felt the reports weren't being followed up enough.
"In my opinion, more could have been done to check on the welfare of [Bradyn], given the number of reports made," she said.
The teacher said child protection had told her that unless the children made disclosures of abuse, it was difficult to proceed.
Bradyn, 9, was beaten to death in January 2016 by his father, Graham Dillon, 41, who is serving more than three decades in jail for the murder.
An inquest into the boy's death is examining what various agencies knew when and the adequacy of their responses.
The court heard that the senior teacher, whose name is suppressed, reached out to the murdered boy's mother last year after Dillon was sentenced. She looked to the mother in the public gallery and made another emotional apology from the stand on Tuesday.
"I wanted you to know there were people looking after [him], and that I'm really sorry about what happened to him but I did my best."
Coroner Margaret Hunter told the teacher: "You did everything you possibly could have and more. You have nothing to answer for."
The teacher gave evidence that the boy had multiple absences, including a number unexplained, from school over 2014.
In terms 3 and 4 there were 27 and 24 days absent respectively.
She said they had noticed bruising on his face, and after making a first report to child protection she checked on him every single morning.
She said she made it her job to make the reports about Bradyn, so concerned was she for his welfare.
At one stage, she asked another teacher to make the report so there was more than just her evidence.
In July 2014, Bradyn came to school with a bruise on his cheek 4cm x 3cm large as well as another smaller bruise on his jawline.
She said Bradyn told her he did not want to talk about it.
In August, the boy came to school with a bruise on the bridge of his nose and "what can only be described as a purple and black ear".
"It was extremely discoloured," she said.
She also noticed his cheek was bruised on the same side as his ear.
The boy's explanation was that he had been play fighting with his father who had thrown him in the air and he had hit the couch.
The teacher said she demanded child protection attend the school to see the marks for themselves.
They arrived shortly before the bell rang for the end of the day and took the boy to hospital for assessment.
The next day, Bradyn's father came to the school and asked to speak to the teacher.
He told her he was angry about the school calling authorities for what he believed was the second time in two weeks, she said.
She said he told her the boy had been put through hell getting health and sexual abuse checks at hospital.
He told the teacher that he had been jailed for 10 years and might go out and hurt someone. The teacher said she took that as a threat.
But Dillon responded that it was not directed at her but that he might get drunk and bash someone up.
He told her he was removing the boy from the school.
The teacher said she informed child protection what had happened.
At one stage she became aware the boy was not attending school and the teacher described trying to find out where he was. She called another school after hearing he had been enrolled there.
The teacher broke down in the stand as she explained how she wanted to ensure the next school was just as vigilant.
It later emerged that after an incident in which Bradyn's mother had taken him to Victoria, Dillon took the boy on holidays for two weeks. He returned with bruises down one side of his face.
After the summer holidays, the boy did not return to school.
The teacher heard he had moved to NSW and the school was unable to trace him.
"I felt that I had reached the end of the road."
Since Bradyn's death a new liaison officer role has been created to improve communication between child protection and the schools.
The inquest continues.