A man convicted of the rape and murder of a nine-year-old girl in western Sydney 30 years ago has been recommended for day release into the community.

Rodney Thomas Clarke was 21 when he broke into a Tregear home in July 1987 and sexually assaulted and then killed schoolgirl Debbie Keegan.

Clarke broke into Debbie's bedroom using a ladder after he noticed that her mother Suzanne was asleep in their lounge.

When he entered the room, Debbie screamed. He put his hands over her mouth and raped the nine-year-old three times.

A court found he then suffocated Debbie while her seven-year-old sister Sarah was lying in her bed in the same room.

Debbie Keegan was nine when she was murdered. (9NEWS)

It's something Sarah Keegan told 9NEWS has haunted her her entire life.

"I remember hearing my sister saying, 'who are you, what are you doing?'," Ms Keegan said.

"And he told her to go back to sleep and he walked out of the room.

"He was gone for a while, and I remember hearing him come back in the room.

"It's pretty hard not knowing what would have happened if I had said something."

The murder prompted a wave of anger and fear to sweep across Sydney.

Groups of parents marched onto the streets of Mount Druitt holding their children's hands as the police manhunt stepped up.

Officers even went from classroom to classroom at Tregear Public School warning Debbie's classmates there was still a murderer on the loose.

Rodney Clarke could be released back into the community. (9NEWS)

Clarke, who was a neighbour of the Keegans, was arrested days later.

According to court documents, Clarke told police, "he did not mean to kill the girl and that he thought she was still breathing when he pulled the covers back over her."

"He could offer no explanation for his decision to have intercourse with her."

He later claimed that he did not act alone and had an accomplice, and it was this man that had killed Debbie. Ten years later he admitted he acted alone.

In 1988, Clarke was sentenced to life in prison for murder and 60 years for three counts of sexual intercourse with a child under 10.

"It is difficult to comprehend that a human being could engage in such conduct in a civilised society," the judge said.

In 2005, Clarke was granted the opportunity for parole and his sentence was redetermined to 28 years. He applied for parole in 2015 and 2016 and he was denied on both occasions.

In March, Ms Keegan received a letter from the Serious Offenders Review Council.

"At a meeting on the 14 th February 2017, the Council formed an initial intention to recommend to the [Correctives] Commissioner that Rodney Clarke's security classification be reduced to C3 … to enable the inmate to engage in external leave programs," the letter read.

In other words: Clarke was recommended for day release.

"He needs to stay [in jail]," Ms Keegan said.

"My family's the one that's been given the life sentence, not him."

NSW Opposition Leader Luke Foley said Debbie Keegan's family should not have to relive this horror every time Clarke applies for parole.

"Nobody thinks this bloke should get out. Why are the victims being dragged through this year after year after year?" Mr Foley said.

Correctives Minister David Elliott said it's just a recommendation to the commissioner and not one that has to be adopted.