Triple child killer Leslie Camilleri has been jailed for 28 years for the murder of Melbourne teenager Prue Bird.

Triple child killer Leslie Camilleri has been brought to justice for the murder of schoolgirl Prue Bird, but how she died and where she is buried will probably never be known.

The Bega schoolgirls killer has been jailed for 28 years for murdering 13-year-old Prue, 21 years after he abducted her from her Melbourne home on a February afternoon.

Victorian Supreme Court Justice Elizabeth Curtain found Camilleri’s claim that he acted alone and that her death was an accident implausible.

“You were involved with others in the abduction of a defenceless 13-year-old girl from the sanctuary of her home in circumstances that must’ve been terrifying for her,” she told Camilleri on Thursday.

“Your conduct bespeaks criminality of a very high order and is demonstrative of a cruel and callous disregard for the sanctity of human life.”

Camilleri, 43, is already serving two life terms without parole for the murders of Bega schoolgirls Lauren Barry and Nichole Collins in 1997.

Justice Curtain said many facts of the Bird case were unclear, but she was convinced Camilleri abducted and murdered Prue with the help of two other unidentified men.

Police believe one of those men was Mark McConville, who died in 2003, and Justice Curtain said his involvement was a possibility.

She said the crime was unsolved until Camilleri confessed and his guilty plea provided some comfort to Prue’s mother Jenny Bird.

“By your plea of guilty, you have at least given Mrs Bird some small comfort that at least one person has been brought to justice and held accountable for her daughter’s murder.”

Ms Bird said she was pleased Justice Curtain concluded Camilleri did not act alone.

“I haven’t been satisfied from the day I reported Prue missing with the police, I’m still not satisfied today, but this was the best I was hoping for – that it was ruled that he didn’t act alone,” she said outside court.

She said she had not given up hope the ruling could one day lead to police reopening the investigation into the involvement of others.

“It leaves me with hope still,” she said.

“I just pray one day I might know what happened to Prue. The truth didn’t come out.”

Ms Bird also said she believed Prue was killed as retribution for her grandmother and her partner making statements to police about the 1986 Russell Street bombing.

Camilleri told police he grabbed Prue off the street while hunting for a man who abused him as a boy and that her death was an accident.

He said he took her, believing she would lead him to the man, then bound her with cables and threw her into the back seat of his car, where she died.

Her body was then dumped at a Frankston tip, Camilleri told police.

But Justice Curtain dismissed his account of how and why he murdered Prue.

She also rejected his claims about the location of Prue’s body, after a police search found no trace of human remains.

“I am not persuaded on the balance of probability that Prue Bird is likely to have met her death as you say she did,” Justice Curtain said.

“Her body has never been found and most likely never will.”

Justice Curtain said Camilleri would forever remain a risk to the community.