The Chief Inspector of Probation says he cannot guarantee the public is being properly protected.
Justin Russell was speaking after his report slammed failings that left a sex predator free to kill Zara Aleena.
He said the “clear lesson” is that staff are overworked.
A murder is committed once every six days by a convicted criminal under probation supervision, figures reveal.
Criminals on licence killed a total of 599 people in the last decade, and an average of 60 every year, Ministry of Justice statistics show.
The grim toll can be revealed after ministers and probation leaders were said to have “blood on their hands” for failings that left sexual predator Jordan McSweeney free to kill Zara Aleena.
Not all the murders recorded can be blamed on probation failings but Chief Inspector of Probation, Justin Russell, has now warned that without urgent Government action to reverse cuts, he cannot guarantee that the public is being properly protected.
A damning report published yesterday found McSweeney, 29, was wrongly considered medium risk by the private firm monitoring him, despite him warning his own anger scared him.
McSweeney got a life sentence and will serve at least 38 years after admitting sexually assaulting and murdering Zara in Ilford, East London.
He had been free for only nine days last year when he stalked the aspiring lawyer, 35, grabbed her and repeatedly kicked and stamped on her head and body resulting in 46 injuries.
During that time, he had failed to turn up for three probation appointments and disappeared from his mum’s house after drinking heavily.
Prison staff submitted 15 concerns about McSweeney, mainly for making weapons and using drugs, but details were not shared with probation.
Justice Minister Damian Hinds has said he was “profoundly sorry” for the “serious failings”.
None of those involved in the management of McSweeney will face any disciplinary action.
Zara’s aunt Farah Naz said “heads should roll”. She said: “Zara’s life was taken and probation have blood on their hands.”
Mr Russell said yesterday there are over 500 serious further offences, including murder and rape, committed on probation each year.
He said: “Until the Probation Service puts those things right, it’s impossible to say that the public is being properly protected from the risks that people on probation pose.”
The “clear lesson” from Aleena’s case is that “overworked staff” do not have time to go over case files, he said.
He revealed he offered to speak to Justice Secretary Dominic Raab to discuss his concerns, adding: “I’m hoping he’ll take me up on that opportunity.”
McSweeney was only classed as medium risk by a Community Rehabilitation Company. CRCs were introduced by ex-Justice Secretary Chris Grayling in 2014 but axed in 2021. They cost almost £500million and led to a rise in killings by people on probation.
Centre for Women’s Justice director Harriet Wistrich said of Zara’s case: “This is only one of a series of murders that might have been avoided over the last few years.”
Labour’s Jess Phillips said: “The truth is we do not monitor these people and we should stop pretending otherwise. There is no monitoring of the most violent, well-known, prolific offenders against women and girls.”
A Ministry of Justice spokesman said: "Serious further offences are incredibly rare and the Deputy Prime Minister has set out plans to overhaul the parole process and invest £155m more into probation to keep the public safe."
