Annette Mason was 15 when she was bludgeoned to death in a house she shared with friends in Toowoomba in November 1989.
She died of blunt force trauma to the head inflicted with a piece of timber found in the laundry.
No one has been charged with her murder.
The inquest resumed in the Coroners Court in Brisbane on Monday to examine when, where and how she died.
Coroner Terry Ryan will also try to determine if anyone should be charged with Annette's murder or manslaughter.
Her family, including mother Judith and sister Linda, were in court on Monday wearing yellow, Annette's favourite colour.
"It's been a very long haul," Judith Andersen told reporters outside court.
"We have been through the mincer a few times.
"Annette was a lovely, normal 15-year-old girl who did not deserve what happened to her."
The 70-year-old hoped new DNA information set to be presented at the inquest would help bring some closure.
The first inquest in 1991 was closed and subject to "reopening at any stage should further evidence become available".
It was reopened in 2018, but then adjourned and further delayed by COVID-19 and DNA tests in New Zealand, counsel assisting the coroner Adrian Braithwaite said.
"I have no idea about the results of any of it but I am hoping it will shed a lot of light onto what happened," Mrs Andersen said of the DNA evidence.
Linda Mason said Annette's grandparents had died without any answers but was confident the inquest would unveil the truth.
"We are hoping by the end of this inquest we have some answers to what happened to Annette," she said.
"The long wait between the last inquest and this one, being on hold has been excruciating."
The reopened inquest is being conducted under changes to state legislation that gives coroners more powers to compel witnesses to give potentially self-incriminating evidence.
One of the nine witnesses set to give evidence this week is person of interest Allan McQueen.
Robert Speedy on Monday denied hearing McQueen confess to Annette's murder or "flogged a sheila in Toowoomba" while they were both inmates at Sir David Longland Correctional Centre in 1992.
Mr Braithwaite said it had been suggested McQueen told his childhood friend Speedy in prison that he had "put the hard word" on Annette in November 1989 before hitting her over the head with a piece of wood when she knocked him back.
Speaking via telephone from Arthur Gorrie Correctional Centre, Speedy, 55, said: "No way in the world. Why would anyone want to tell me that?"
The inquest continues.
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