The 22-year-old man was arrested in 2016 in Greece on the border with Turkey.
He would then have been arrested at the age of 30 with a man, even he from the Gothenburg area, who had previously been convicted of terrorist crimes.
At the arrest, the police discovered that men were carrying knives, fighting equipment and almost SEK 60,000, divided into different currencies.
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The police suspected that the men were on their way to Syria to join the Islamic state of IS, and in 2017 the men were sentenced to 15 years in prison against their denial.
Despite the long prison sentence, one of the terrorists has now been released, P4 Göteborg reports.
According to information from the channel, the 22-year-old man has now returned to his family in Sweden.
The Ministry of Foreign Affairs confirms the data for the radio without considering why the man was released.
"We have no information about it and, when released, he is no longer a consular case for the foreign government," said Rasmus Eljanskog, communicator at the UD, at P4 Göteborg.
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Both men appealed against their statements earlier this year and their judgments were reduced to seven years and three months and nine years, respectively. Why the 22-year-old, who had to sit on his judgment for years, is still unclear.
The 30-year-old is still in Greek prison, but according to information at P4 Göteborg he is also about to be released. However, the data is not confirmed by the UD.