The deportation order for Rakhmat Akilov, an Uzbek national denied a residency permit in Sweden, entered into legal force in December 2016. Swedish police explained that the case was referred to them the following February, but he was not at the address he was registered as living at and could not be found. Akilov had not been flagged as a security risk by security police Säpo.
Thousands of people are being sought in similar circumstances in Sweden, and it is often difficult to locate them, police have noted. False address information like using a PO Box as a registered address can make it tough to track the person down.
"The biggest challenges police face when attempting to enforce deportation is the person's identity isn't always reliable, not all countries want to take back their citizens if they don't return freely, and many disappear when they get their decision," national border police head Patrik Engström said on the police website.
"He wasn't at the address he had given and there was nothing to say he would be dangerous. Forced deportation to Uzbekistan is also rare and done only with caution," he added.
READ ALSO: Stockholm terror suspect admits truck attack
The suspect's country of origin is worth noting. Swedish police refer to a judicial position adopted by the Migration Agency (Migrationsverket) in 2015, in which the agency advised "general caution" when assessing returning someone from Uzbekistan to their homeland by force.
"With Uzbekistan it's a special situation. Some years ago there was a ruling from the European Court of Human Rights where someone was due to be deported to Uzbekistan, and the court judged that in Uzbekistan there's so much repression when people return that even just going to Europe and seeking asylum, for example, is enough to be subjected to torture and inhumane treatment," Tomas Fridh, a lawyer specializing in migration law who has previously worked at the Migration Court in Gothenburg told The Local.
"If there's any suspicion of criminality then there's a concrete risk of inhumane treatment. As such Sweden is bound by that, and that's why Migrationsverket made the statement it did saying great care should be taken with deportation to Uzbekistan," he added.
Indeed, on their website police explained that a general rule is that when attempting to deport someone to Uzbekistan the person should only travel of their own free will, without an escort and without agencies in the country being contacted beforehand.
"When people are given a rejection notice in Sweden they have a duty to return by themselves, and there's nothing that clearly suggests if someone travels back to Uzbekistan of their own free will they would have a problem in the home country. Agencies in Sweden try to get these people to choose to travel back to Uzbekistan," Fridh explained.
Human Rights Watch describes Uzbekistan as a country with an "abysmal human rights record" where "torture is endemic in the criminal justice system".
Migrationsverket's head of special operations Oskar Ekblad has previously noted that deporting someone is not as simple as it may seem.
"In many cases enforcement work is so difficult that it is not immediately possible to deport them," he said in December 2016, explaining that circumstances in the person's homeland can stall the process.
Some politicians in Sweden have called for the rules in the area to be looked at in the aftermath of the Stockholm attack, but Interior Minister Anders Ygeman has said that the investigation into what happened on April 7th will flag up any failings in the area if they exist.
And migration law expert Fridh isn't sure what more can be done at present:
"I think there's very little we can do. Sweden is one of the countries that works most actively to send people back who have received a rejection notice, in line with the Dublin regulation. In general it's a very difficult thing to pull off, to deport people who have had a rejection notice."
"I find it difficult to see how much more effective we can make it, in any case in the current situation. There are thousands of people without residency permits in countries across the whole of Europe, that's the situation in the western world. I haven’t seen any concrete proposals on how this could be made better," he concluded.