Bridgette, also known by the nickname Biddy, was killed by a teenager known to her in rural NSW in 2020.
The NSW Supreme Court found Biddy's killer, who cannot be identified for legal reasons, was not criminally responsible due to mental illness in 2021.
Much of the case was anonymised due to the ages of Biddy and the perpetrator, while graphic details surrounding the killing are protected by a court order.
Biddy's identity was made public in mid-2024, when her parents and campaigners from Advocacy Australia launched a petition calling for an inquest and a review of the handling of the case.
The inquest is due to open on Tuesday before NSW State Coroner Teresa O'Sullivan.
It will examine responses to the perpetrator's mental health, including from family, medical practitioners and the school system.
Biddy's mother Rebekah Keukenmeester will be relieved to see the inquest begin, Advocacy Australia chair Clare Collins said.
"Not only had she lost her beautiful child ... her child had been erased, so her whole identity had been removed," Ms Collins told AAP.
"To get to this point now has made an enormous impact on Rebekah; she feels that the world now knows about Biddy."
Ms Collins said it was hoped the inquest will answer questions about the lead-up to the killing.
"That is to find out who knew what, when they knew it, with the hope of preventing this from happening again," she said.
 "All these signs, all these activities that went on beforehand, can be a warning to other people."
Biddy's father Dominic Porter said it had been difficult to stay silent about her death for so long.
He hoped greater public awareness of the family's experience would lead to better support for victims.
"Some good has to come out of this somewhere," Mr Porter told Nine's A Current Affair on Friday.
"That's what Biddy would want and that's what I want."
Since the family spoke out on the fourth anniversary of Biddy's death, her story has received national attention.
The petition to NSW parliament attracted more than 20,000 signatures.
That also led to a separate parliamentary inquiry into the forensic division of the Mental Health Review Tribunal, which is set to examine case management of forensic patients and victim support.
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