But the country’s leading terrorism expert, Magnus Ranstorp, said investigations are the only way to “bring these people to justice.”
In an interview with news agency TT, Ranstorp, who is the head of research on terrorism and countering violent extremism at the Centre for Asymmetric Threat Studies at the Swedish Defence University, said the idea of investigating all returning fighters should at least be discussed.
“There is very little opportunity to bring these people to justice unless there are preliminary investigations of them. And it is necessary if you are to have access to go through, for example, their phones and social media accounts,” he said.
There are different views within the EU on how to deal with suspected Isis terrorists returning from Syria and Iraq. Some countries presume that anyone who spent extended periods in areas controlled by Isis has likely committed crimes, according to Hans Ihrman of the Swedish Prosecution Authority's National Security Unit (Riksenheten för säkerhetsmål).
“In principle, there is a presumption that one has been involved in either some form of a war crime or terror crime,” Ihrman said.
Foreign fighters found by chance
In Sweden, however, suspicion of a specific crime is required in order to initiate a preliminary investigation. If there is no concrete information to work off, the police's ability to access any digital evidence, for example in returning foreign fighters’ phones, decreases drastically.
In one case, police accidentally found evidence of terror crimes while conducting a drug investigation. As a result, two men in western Sweden who were not affiliated with Isis were convicted of terror offences in Syria for having participated in an execution after police found video evidence of the murder on a USB stick.
If the police were given the ability to investigate anyone returning from Isis, more Swedish citizens would likely face charges, Ranstorp said.
“Of course it would make things easier. Then police would have found much, much more,” he said.
But Ihrman said he does not want to see special regulations for returning Isis supporters.
“Absolutely not. An absolute minimum requirement for initiating a legal procedure is that there is some form of evidence or circumstances that can actually constitute a criminal offence. Just simply being present in an area where horrors have occurred should never be a sufficient basis for suspicion,” he said.
Ihrman would not divulge how many of the 150 Isis supporters who have returned to Sweden have been the subject of preliminary investigations. But only one has been prosecuted and no one has been convicted of crimes committed in overseas conflict zones.
No consular help
One consequence for Swedes who travel to Syria is that they are cut off from receiving any consular assistance from the state.
“You were advised not to travel there already in 2012, maybe 2011. If you still go there, you cannot count on any consular assistance from the Swedish state. That's a no,” Prime Minister Stefan Löfven said.
But the PM avoided giving a straight answer to the question of whether it would be appropriate to revoke the Swedish citizenship of Isis supporters who took part in the fighting in Syria.
“That is something that the relevant ministry can comment on. But we have to show very clearly that we have advised against travelling to Syria and therefore one cannot count on receiving any consular support in Syria,” Löfven said.
Gothenburg police chief Erik Nord, on the other hand, was more direct about calling for the revocation of foreign fighters' citizenship.
“Revoking Isis terrorists' Swedish citizenship is a part of the solution. Simpler, cheaper and more effective than prosecuting them in Swedish court,” he wrote on Twitter.
In an interview with Göteborg Posten, he said Swedes would be deterred from leaving for Syria and Iraq if they knew it would cost them their citizenship.
“We are too soft with these terrorists,” he said.
Legislation coming too late
According to Sweden's security police agency Säpo, about 100 suspected Swedish Isis terrorists remain in the conflict zone. Ranstorp said the authorities should consider investigating those who return to Sweden.
“It is actually quite reasonable because they have been down in a war zone,” he said.
In neighbouring Norway, which criminalized co-operation with terrorist organizations in 2013, a significantly higher number of returning jihadists have been investigated and prosecuted. The Swedish government is aiming to pass similar legislation later this year, but many feel like the move comes far too late, and Ihrman said he does not have high hopes for the outcome.
“The objection will of course be that these people belonged to the organization at a time when doing so was not formally criminalized. Then we would have to prove that they were still part of the terror organization after the legislation came into effect. That will be quite difficult because Isis as a group today is basically eliminated,” Ihrman said.
It is estimated that around 300 people have left Sweden to join terror groups in Syria and Iraq since 2012. Roughly half of them are believed to have returned to Sweden, while around 50 are thought to have been killed and another 100 remain in the region.