The man who murdered Doncaster teen Masa Vukotic was on bail over death threats, was  under a court supervision order, and had a long criminal history of sexual violence against women, raising more serious questions about Victoria's justice system.

The long and violent history of Sean Christian Price, which can now be revealed after he pleaded guilty to rape, prompted Victorian Premier Dan Andrews to admit: "Our justice system failed Masa Vukotic. It failed her family and friends. It is a tragedy that must force change.

"That Sean Price was free and largely unmonitored in our community was a catastrophic failing of the criminal justice system.

"We have been limited by the proceedings before the courts. But from the moment Sean Price handed himself into police, the government has been working to fix the system that allowed him to be in the community ... Our job is to protect Victorians and we will repair this broken system."

He said, however, that "this problem goes beyond Sean Price".

Price's rape came as part of a two-day crime spree last March during which he also murdered Ms Vukotic by stabbing her 49 times.

​We can now reveal that Price:

– had been in jail or forensic psychiatric institutions for most of his adult life after a rape and burglary spree in the eastern suburbs of Melbourne in 2004, which started when he was just 18 years old;

– attacked then health minister Tony Abbott on a visit to the Thomas Embling forensic hospital in 2006 because, he said, "he annoyed me", a source said;

– spent time in Corella unit in Ararat for serious sexual offenders, but had twice violently destroyed property there and assaulted officers and other inmates;

– was put under a 10-year supervision order pursuant to the Serious Sexual Offenders legislation in 2012;

- was on bail at the time of Ms Vukotic's murder because he had been charged with threatening to kill prison guards during a stint in Port Phillip prison. He told guards: "When I get out I'm gonna ... slit kids' throats." Ms Vukotic was killed when he stabbed her in the neck.

– Two days after Ms Vukotic's murder, Price visited Sunshine police station to report for bail, but he was allowed to walk out again, after which he attacked, choked and robbed a man in an elevator, then digitally raped a woman before reporting back to Sunshine Corrections Office and gave himself up;

– prosecutor Michelle Williams asserted that the rape had occurred because Price had wanted to "get his rocks off" before receiving what he knew would be a long stint in jail for murder;

– Price had told psychologists over many years that he enjoyed raping women, which he called a "natural high", and also taking drugs, a "chemical high", and that he had particular hatred for women he considered rich.

On October 2, 2104, police in Werribee put Price on bail for the threat to murder prison guards. He was not on parole because he had served all his time in jail, and had to be released.

Sources say Price abided by all his bail conditions, including living in an apartment in west-suburban Albion, where he was supposed to, and obeying his curfew and reporting conditions.

However, it's unclear whether he was under any kind of mental health care, despite his long history of psychiatric disturbances.

Horror over these facts, which come on the heels of the rape and murder of Jill Meagher by Adrian Bayley, who was on parole at the time, has prompted fresh questions about the quality of the Victorian justice system.

Mr Andrews said yesterday that, hours after charges were laid against Price on March 20, the state government had "launched an immediate assessment of every single serious sex offender on a supervision order," and that, as a result, "there have been changes to strengthen supervision".

In May the government also appointed an independent panel, led by former Supreme Court Judge David Harper, to review how dangerous sexual offenders are managed. The review is due to report to the government by October 30.

Price's first offences were multiple counts of rape, indecent assault, robbery and stalking. For almost two years in 2002 and 2003, he followed women and girls and attacked them, sometimes in their own home. His youngest victim was 13 years old.

Victims of Crime commissioner Greg Davies said the system had failed Masa Vukotic.

"When does the system recognise that the rights of the community at large, outweigh the rights of one individual?" Mr Davies told 3AW Mornings, "Particularly when that individual has had multiple opportunities to mend their ways".

Sean Price: a history of violence

July, 2003: Sean Price, 19, hands himself in at Doncaster police station over a series of sex attacks in Melbourne's eastern suburbs during a six-week period from May to June 27. He is eventually charged with 22 offences, including some that date back to 2002. He asked his victims for directions before following them home, and was identified by a blemish on his face. "There is no evidence there is any planning other than the common rat cunning of a criminal," a policeman said at the time. He had been living at Donvale.

October, 2004: Sentenced for the series of sex attacks to eight years and two months at Thomas Embling Hospital, with a minimum of five and half years. Had already served more than 15 months. Convicted of offences including rape, stalking, robbery, making threats to kill and aggravated burglary. Registered as a sex offender.​

​January, 2012: Sentenced to four months' prison for recklessly causing serious injury while at Thomas Embling.

May, 2012: Released on a supervision order, to start on May 14 and continue for 10 years. Moved to Corella Place, a village-style complex for sex offenders, in Ararat.

January, 2013: Convicted of criminal damage and unlawful assault for attack on cars at Corella Place. Sentenced to three years' imprisonment.

June, 2013: Sentence for criminal damage and unlawful assault reduced to 10 months, almost six of which have already been served.

April, 2014: Sentenced to nine months for another outburst at Corella Place, which included charges of intentionally cause injury, unlawful assault and criminal damage.

October 2, 2014: Released from prison, moves to tiny flat in Albion where he lives alone.

March 17, 2015: Murders Masa Vukotic in Doncaster.

March 18, 2015: Police release CCTV of man boarding a bus and running past a school shortly after Masa was killed. Price is recognised by a Department of Justice employee.

March 19, 2015: Price goes on a rampage in the western suburbs, robbing a man in Sunshine, attempting a carjacking, and raping a woman at a bookshop, before handing himself in.

August 17, 2015: Pleads guilty to murder and robbery.

August 27, 2015: Pleads guilty to rape.