Sweden is ending its investigation into the mysterious explosions that blew up the undersea Nord Stream pipelines after concluding the country's courts do not have jurisdiction over the case.

In a statement issued Wednesday, Swedish prosecutor Mats Ljungqvist said officials had concluded the probe should be discontinued after a "systematic and thorough" investigation.

However, he added that Germany's inquiries are ongoing but "due to the secrecy that prevails in international legal cooperation" he was unable to comment further on the details unearthed by either side.

Along with Berlin and Stockholm, Copenhagen has also launched an investigation into the two blasts that destroyed three of the four strands of the Nord Stream 1 and 2 pipelines, which connected Russia's Siberian gas fields to Germany through the Baltic Sea, in September 2022.

But the explosions remain shrouded in mystery, as investigators have so far been unable to identify a culprit.

Sweden and Denmark have labeled it a deliberate act of sabotage, and Swedish prosecutors later found traces of explosives at the site of the blasts.

German investigators, meanwhile, have traced the explosives back to a yacht which they suspect was used to transport them to the blast site.

The uncertainty around the attack has fueled a range of theories seeking to uncover who was responsible.

Several countries have been publicly blamed for the explosions, with varying degrees of evidence. Ukraine has blamed Russia for the bombing, and Poland has also hinted that Moscow was responsible, which the Kremlin has denied.

Moscow's version is that the U.K. is to blame instead, without presenting any evidence to support the assertion. That claim that has been dismissed as "invented" by the British defense ministry.

Media reports from the New York Times and several German publications have also raised the possibility that a pro-Ukrainian group could have been behind the blasts.

In a June interview with POLITICO's parent company, Axel Springer, Ukrainian President Volodymyr Zelenskyy insisted Kyiv was not responsible. “I am president and I give orders accordingly,” he said. “Nothing of the sort has been done by Ukraine. I would never act that way.”