LONDON - When Usman Khan left prison last December after serving half of a 16-year sentence for his part in a plot to blow up the London Stock Exchange, and for planning to establish a terror training camp in Pakistan, he was thought to be making good progress towards being de-radicalized and was seen as a poster boy for Britain’s rehabilitation programs.

Cambridge University, which ran one of the programs Khan attended, was even considering offering him a place to study.

But now following 28-year-old’s dramatic knife attack Friday on London Bridge during a university-sponsored justice event, which left two people dead and three seriously injured, the early release of convicted terrorists, as well as de-radicalization programs, are coming under immediate scrutiny amid accusations that militants are gaming the rehabilitation system and hoodwinking authorities.

Some criminal justice experts say Khan played the rehabilitation system cleverly to secure his release and to lull his probation officers into allowing him to travel unsupervised from his home in the English county of Staffordshire to London for the justice event, where he killed two rehabilitation tutors, 25-year-old Jack Merritt and 23-year-old Saskia Jones.

“Despite the monitoring he was subjected to, he was able to convince everyone he was well on the way to being a reformed character,” according to Harry Fletcher, a criminal justice expert and campaigner for victims’ rights. Khan’s attack wasn’t opportunistic, but deliberately planned, say British counter-terror officials.

With fears mounting that other recently freed terrorists may also be playing the system, a crackdown has been launched that’s likely to see a large number of them returned to prison. One of Khan’s close associates, 34-year-old Nazam Hussain, who was freed from jail the same day as the London Bridge killer, was re-arrested Sunday on suspicion of preparing terrorist acts.

At least 74 freed terrorists are being vetted again, according to British Prime Minister Boris Johnson, who said in a broadcast interview Sunday that they all needed to be “properly invigilated so as to make sure there is no threat to the public.”

Britain's Prime Minister Boris Johnson, center, Labour Party leader Jeremy Corbyn, right, and Mayor of London Sadiq Khan take part in a vigil in memory of the attack victims, at Guildhall Yard in London, Dec. 2, 2019.

Freed terrorists are required to follow a strict set of rules, including not using the Internet, not associating with former accomplices, observing a curfew and attending only approved mosques. They are required to wear electronic ankle tags so their movements can be monitored. Khan wore one during Friday’s attack which unfolded at a conference near London Bridge sponsored by Cambridge University’s “Learning Together” program, which aims to help assist in the rehabilitation of violent offenders.

An election issue

The London Bridge attack, which ended after the knife-wielding Khan was confronted by conference attendees, including former offenders, and staff and shot dead by police, is dominating election campaigning with Johnson quick to go on the attack and blame previous Labour governments for the system of early release for convicted terrorists.

Johnson says violent offenders “must serve every day of their sentence, with no exceptions.” He added: “If you are convicted of a serious terrorist offense, there should be a mandatory minimum sentence of 14 years - and some should never be released.”

Labour politicians have hit back, saying it is recent Conservative spending cuts that are to blame and have called for a full investigation into Khan’s prison sentence and subsequent release. And Jeremy Corbyn, the leader of the main opposition Labour party, says convicted terrorists should “not necessarily” automatically serve their full prison sentences. “I think it depends on the circumstances and it depends on the sentence but crucially depends on what they've done in prison,” Corbyn said.

But amid the political party wrangling, criminal justice professionals and lawmakers who have built up expertise on de-radicalization say knee-jerk reactions and politicization of the challenge will not help improve rehabilitation programs or answer difficult questions surrounding their effectiveness and whether a militant can be de-radicalized.

Police officers patrol the scene in central London, Dec. 1, 2019, after a knife attack on London Bridge.

Programs' efficacy in question

Some prison experts have warned for months about a lack of rigor with the programs but have also raised concerns about the resources being devoted to de-radicalization, arguing much more money needs to be spent. Among them, former top prosecutor Nazir Afzal, who says Friday’s terror incident could have been avoided.

“What makes me angry is that for some years we have been talking to the government, not just me but many others, about these de-radicalization programs. These programs are delivered by well-meaning people on a shoe-string and are under-resourced and involve the ticking of boxes, but no ticked box has saved anybody’s life,” he says.

Others say more fundamental thinking needs to be done and it is not just a question of resources. “Our judicial system isn’t able to cope. We try to rehabilitate but the two people who were killed were people who were trying to help to give this person a second life and yet he wanted to kill. We need to better understand the mindset of somebody like that,” Tobias Ellwood, a Conservative lawmaker and former army officer, told Sky News.

Former prison governor, Ian Acheson, who in 2015 led an independent review of how Islamist militants are handled by the country’s prisons and probation system, says the entire system is deeply flawed, marked sometimes by naïveté and a “toxic combination of arrogance, defensiveness and ineptitude.” He complained in his report that the “screening tools to detect and programs to tackle radicalized behavior were rudimentary in-house creations with former terrorist offenders telling us how easy courses were to ‘game.’”

He argues Britain’s criminal justice system is “unsuited to managing the risk of religious extremists with a martyrdom complex coming from a moral universe far away from the professionals responsible for their management.”

But writing in The Times newspaper, Acheson said “it would be a shame — possibly counterproductive — to go for the punitive response that the public will understandably demand. Few terrorists will be locked up forever and we need to ensure that those released have a chance to recant their hateful beliefs and join society again.”