Justice Kirk, 5 holds a sign about his uncle Clinton Speedy-Duroux, who was killed aged 16 in 1991.

Justice Kirk, five, holds a sign about his uncle Clinton Speedy-Duroux, who was killed aged 16 in 1991. Photo: Kate Geraghty

The state government has given the green light to a parliamentary inquiry into the murder of three Aboriginal children in Bowraville in the 1990s, in a breakthrough for the children's grieving families.

The Legislative Council voted unanimously on Tuesday in support of the inquiry into the murder of Colleen Walker-Craig, 16, Evelyn Greenup, 4, and Clinton Speedy-Duroux, 16, who went missing separately from the same road in the northern NSW town over a period of five months from September 1990.

A white man, well known to the close-knit indigenous community, stood trial for two of the crimes but was acquitted. He was not tried for the murder of Colleen as her body has never been found.

Evelyn Greenup, was murdered in Bowraville, in 1990.

Evelyn Greenup was murdered in Bowraville in 1990. Photo: Supplied

The community believes the first police investigation was botched and crucial evidence showing the similarities between the cases should have been admitted in court.

"It's a small step in the right direction," Colleen's mother, Muriel Craig, said. "I want them to know about how my life is, every day. Every day it's a challenge. I've got to wake up knowing that Colleen is not with me."

Ms Craig said her family had "kept me in my right mind because I know that I've got to be there for them. Otherwise, I don't know, I might have done something silly a long time ago."

Colleen, who would have been 39 this year, was the second-eldest of five children. She was "very close" to her big sister, Rose, who is now 40.

"At the time when she went missing Rose had a baby boy," Ms Craig said. "The first grandchild [of 11] that I had. We're not only missing out on her life but she's missing out on our lives. In a way, I feel robbed of that. She was a very spirited girl and loving and caring."

The families of the three children urged Attorney-General Greg Smith last year to apply for a retrial after important new evidence emerged. He declined but the government has offered a $250,000 reward for information leading to a conviction for all three murders.

Police Minister Michael Gallacher said the inquiry showed "our support to [the families], as grieving victims, that we understood that there was a need for them to have an opportunity to speak".

"They should never believe ... that this house is not listening to them," Mr Gallacher said.

The Standing Committee On Law And Justice, chaired by Liberal MP David Clarke, will inquire into and report on the "family response" to the murders in the first half of next year.

The families will be given an opportunity to "appear before the committee and detail the impact the murder of these children have had on them and their community".

Greens MP David Shoebridge, who led the push for the inquiry, said the committee could "never conduct a murder investigation" but it could provide a forum for hearing the families' grief.

"The families and the community after 23 years must be heard by this house," he said. "It will be an extremely distressing and difficult inquiry for all participants on it, but more important for the family members and the community who come forward."

The man who stood trial for two of the murders now works with Aboriginal children in Newcastle.