Probation Service whistleblowers are warning that public safety is at severe risk, because they no longer have the resources to properly supervise offenders in the community.
Re-offending rates for some of the most serious crimes, including murder, rape and other violent offences have risen by 26% since the Government reorganised the probation system in 2014.
Probation officers have told Sky News they see a direct correlation between the rise in serious re-offending and their inability to effectively monitor offenders.
Under the reorganisation, the publically run National Probation Service (NPS) now deals with the most high-risk offenders, while the supervision of low and medium-risk offenders has been farmed out to 21 privately run Community Rehabilitation Companies (CRCs), who secured contracts worth almost £4bn over seven years.
But many of the CRCs have struggled to manage their caseloads with the resources available.
One whistleblower, a probation officer with one of the CRCs, said staff numbers had been cut in half, but her caseload was as big as it ever had been.
"We now have less time with our cases and rehabilitation has gone out of the window," they said.
"We're being forced to telephone offenders because we haven't the time to meet them face-to-face.
"How then can you read body language to tell if they're reoffending, whether they're back on drugs or involved in domestic abuse."
The officer said she believes the public are being put increasingly at risk.
"Our communities are not as safe as they used to be because we're not able to monitor offenders effectively anymore."
Conner Marshall, 18, from Barry in South Wales, was murdered by an offender who was under the supervision of a local probation company.
David Braddon, a 26-year-old man from Caerphilly, murdered Conner while he was being monitored under a community sentence after being convicted for drugs offences and assaulting a police officer.
He had missed eight probation appointments.
A report by the National Offender Management Service found there were times staff could have "monitored his community order more robustly".
Conner's mother Nadine said: "It was just horrific to learn he (Braddon) was known and the whole case was a shambolic state. We've tried to get answers, from the authorities, but they've been continually obstructive."
Conner Marshall's death is an extreme example, but the probation officers Sky News has spoken to are firm in their belief that many others are at risk without significant reinvestment in the service.
Another whistle-blower, who works for the NPS said even the publically funded national service had become increasingly dysfunctional, largely due to budget cuts.
He said: "Since the break-up of probation, the workloads for the private companies and the National Probation Service have risen exponentially.
"We've got a shortage of staff, we're not training enough new staff and that makes it very difficult for us to both protect the public and protect our staff.
"Some staff members are increasingly going off with stress related illnesses, and others are quitting altogether."
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The Government is still committed to making the new probation system work and has just bailed out the struggling private sector probation companies to the tune of £340m.
While acknowledging the probation system needs to improve, the Ministry of Justice said the reforms which had already been introduced had led to 40,000 previously unmonitored short-term offenders now being supervised in the community.