Four convicts, three of whom are Swedish citizens and one a Tunisian with a residence permit in Sweden, were sentenced for preparing a terrorist act in 2010 at the headquarters of the Danish newspaper Jyllands-Posten over Muhammad cartoons and intended to "kill as many as possible".

Despite being sentenced to 12 years' imprisonment each in 2012, the men will be released this Saturday, having only served two-thirds of their punishment, a practice common in the Scandinavian penitentiary system.

After the judgment, the men were moved to various institutions in Sweden. According to the Swedish Prison and Probation Service, all the prisoners had been reported for threats and violence against staff and other prisoners during the time served. One of the terrorists had to be isolated after suspected attempts to radicalise fellow inmates. However, none of the cases constituted sufficient reasons to postpone the conditional release, which becomes applicable after two-thirds of served punishment, including the time as deprived of liberty before they are convicted.

One of the terrorists visited al-Qaeda* training camps in Pakistan, whereas another one attempted to contact terrorist groups himself on several occasions. Furthermore, the action was sanctioned by al-Qaeda's top leadership, the daily newspaper Dagens Nyheter reported.

"It is not possible to say with certainty that they will absolutely relapse and become dangerous upon release. But in such crimes there is a great risk of relapse", Magnus Ranstorp, a senior researcher at the National Defence College and one of the nation's leading experts on terrorism, told Dagens Nyheter.

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According to Ranstorp, former terrorists tend to return to their previous environment after serving a penalty. There, they are worshipped as "as rock stars".

Sweden's Security Service (SÄPO) can also decide on post-release monitoring, which has been approved for all four involved in the Jyllands-Posten terrorist plot. In two of the cases, the Prison and Probation Service justified its assessment with a high risk of relapse, in effect repeating Ranstorp's take.

"The problem is that there are no special efforts after release. They get assigned a contact person from the probation service, but are pretty much left for themselves they come out", Magnus Ranstorp said, lamenting the absence of programs to rehabilitate, re-socialise and re-integrate the extremists.

According to Ranstorp, this is a neglected area internationally, which is all the more important as about 1,500 terrorists are about to be released in Europe in 2019. Still, he argued, some countries have begun to discuss compulsory programs as prerequisite for conditional release, while Germany and Denmark have invested in special talks during prison time.

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In 2010, the four Islamists living in Sweden and currently aged 37 to 52 planned to carry out a bloodbath at the headquarters of the Danish newspaper Jyllands-Posten, which in 2005 published satirical drawings depicting Prophet Muhammad. According to the Danish Security Service (PET), the Islamists aimed to "kill as many as possible". In connection with the arrests, carried out in collaboration between Danish and Swedish security police, weapons, ammunition and duct tape intended to bind people were found.

* al-Qaeda is a terrorist organisation banned in Russia