Letting offenders who've committed some of the most horrific crimes back into the community is a decision many will struggle to come to terms with.

Eyebrows were certainly raised when it was revealed murderer Joseph Bagley, who had been living in Maidstone, was arrested last year after three months on the run, was released despite officials knowing he had a history of absconding.

However, the work of the government's Parole Board - an independent body charged with deciding whether such releases are safe - is a complex one, says its chief executive.

Martin Jones, who lives in Maidstone, told KentOnline how the board - made up of more than 250 people including judges and psychologists - deals with some 25,000 cases a year, about a quarter of the prison population.

Around 300 pages of background about the offences they've committed and their behaviour in the time since are pored over, before the most serious cases are sent to a full hearing with two or three members of the board.

Evidence is heard from the probation officer, prisoner officer and of course the individual themselves, before deciding whether they can be released, whether they should stay in prison, or be moved to open conditions.

"Much like a jury, the panel takes a majority view and it's possible the panel can be split but in 99% of cases, a decision is unanimous," Mr Jones said.

"The view is most parole board members will see across their career hundreds of people who have committed serious offences.

"Where decisions are split, the trick will be quite a few hours of detailed debate before making a final decision.

"If we don't make a decision, the case would be reheard to the expense of the public purse, and can rumble on for six months."

The process from start to finish tends to take up to nine months and involves a number of stages, including in some cases lie detector tests - albeit not quite with the flashing lights seen in the movies, Mr Jones added.

Technology is playing an increasingly prevalent role, however, with satellite tracking introduced last year to help monitor movements post-release.

The chief executive said: "If you have a particularly vulnerable victim, one of the release conditions might be that they're tagged with an electronic device so they can be tracked.

"Say the victim is from Maidstone, you might say 'you're not allowed to go back to Maidstone without special circumstances', which might be their mother's funeral, for example.

"The second you enter a zone you're not supposed to be in, it will trigger an alert letting us know that the conditions have been breached.

"I expect the numbers will grow significantly over the next few years - it's only been available for a few months.

"Projections suggest we'll be looking at many thousands of people being tagged in the community, provided the level of risk merits that.

"The first three to six months are the riskiest, so the idea might be to tag them for that period. By that time the hope is they may have settled back into the community."

Overcrowding in prisons, and the problems that came with that, is much-discussed in the media, but Mr Jones insisted there was no pressure from ministers towards the board to help relieve those issues by releasing more prisoners.

In the case of Bagley, who received a life sentence in 1978 for killing a taxi driver, he failed to return to his home last May, a direct breach of his release conditions.

A three-month manhunt ensued before he was eventually found in Chartham, near Canterbury, just days after the Crimestoppers charity announced a £3,000 reward for information on his whereabouts.

Mr Jones said: "Generally speaking, there is one failure for every 1,000 cases, one person who does something wrong, as Joseph Bagley did in this case.

"They tend to go and hide for a period - very few are criminal masterminds who will fly off in a helicopter."

Last summer, the Government introduced a mechanism allowing people to challenge parole board decisions, whether that's the victim or the prisoner themselves - an idea Mr Jones said was way overdue and may help provide further scrutiny in future.

"A victim can now also request a summary of the board's findings, before that it was secret," he said.

"They might be told a decision but not the reason why and that seems bonkers to me."

To get the latest updates on ongoing cases, police appeals and criminals put behind bars, click here.

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