A child protection bureaucrat responsible for managing Bradyn Dillon's case file was burdened by an "absolutely unsustainable" workload that eventually led her to take stress leave, a court has heard.
In late 2014, a little more than a year before the boy was brutally murdered by his father, seven Victorian case workers were expected to manage 20 children's cases at a time.
But up to 160 cases were officially "unallocated" and put in the bureaucrat's care.
A coronial inquest into nine-year-old Bradyn Dillon's death resumed on February 17.
The Canberra boy's last months were marked by beatings at the hands of his father Graham Dillon, before he killed him with a final beating and blow to the head in February 2016.
Graham Dillon is serving more than 36 years in jail for the murder.
In the ACT Coroner's Court on Tuesday, the bureaucrat - appearing as a witness - said there was no way Victorian child protection authorities "could have kept going" with the resources they had in 2014.
Since managing Bradyn's file, three times the amount of case workers had been put on to handle about the same number of cases, she told the court.
"It was absolutely unsustainable," she said.
"You weren't able to give the cases the time they actually deserved."
The bureaucrat - whose name is suppressed, like other witnesses - said she didn't open an emailed document supporting authorities' argument Bradyn should live with his mother in November 2014.
She told Coroner Margaret Hunter she could receive about 100 emails a day and would "scan" their subject lines to determine their urgency.
Instead, Victorian authorities relied on other evidence, including a summary of events the bureaucrat said "was too basic" and "could have been provided in greater detail".
A Victorian magistrate on November 17, 2014 ordered Bradyn be returned to his father's care in Canberra.
The bureaucrat said she didn't have complete faith in Victorian authorities' then-solicitor, who was in court to argue in favour of Bradyn staying with his mother.
"I recall feeling frustrated ... in regards to his lack of submissions [in court on November 17]," the bureaucrat said.
"[The magistrate's] comment was that [Bradyn's mother] unilaterally removed [Bradyn] ... [and] she should have gone through proper processes."
The court previously heard Bradyn's mother drugged his abusive father, before taking the boy to Victoria in an attempt to rescue him from further violence.
The bureaucrat said that during interviews prior to the magistrate's decision, Graham Dillon had told her he had difficulties sleeping because Bradyn's mother took him.
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She described Dillon as "insincere", and said Bradyn's mother seemed to "genuinely fear" him.
"The house [where Bradyn and his mother were living in Victoria] was suitable ... there were no red flags, there were no concerns whatsoever," she said.
When the bureaucrat relayed the magistrate's decision to Bradyn and his mother, the boy was "hysterical" and said Dillon would throw him on the couch and bruise him, she told the court.
The bureaucrat said she was "confused" when Bradyn later ran to his father, which she conceded could have been for "self-preservation".
While the bureaucrat had the power to keep Bradyn in authorities' care, she did not know if Dillon's living environment was "unsuitable".
"I felt that the decision had been made and we had to follow the process in regards to it," she told the court.
The bureaucrat said she had concerns about Bradyn's safety, but did not have the "factual evidence" to back those concerns up in court.
The inquest continues.