Nord Stream trial: How German police followed the evidence – to Ukraine

BySarah Rainsford Eastern and Southern Europe correspondent.

Key points

• When Serhii K crossed into Poland, he was detected, but by 13 August 2025, Germany had identified its key suspect and this time.
• Prosecutors say "high-performance explosives" were planted approximately 80m (260ft) below the surface: four devices weighing up to 27kg each, activated with timers.
• Under Germany's privacy rules, he will be named during the trial only as Serhii K, but during extradition proceedings he was identified as Serhii Kuznetsov.
• After his extradition to Germany and months in isolation in a high security prison, Serhii K will go on trial in Hamburg, next week.
• The case since built by investigators alleges that Serhii K entered Germany for the Nord Stream attack on a forged passport, probable issued by Ukraine's security services.

Serhii K appeared relaxed as he checked in to the glamping resort near Italy's Adriatic coast with his wife and young children.

Dressed in shorts, sandals and a dark baseball cap, the former Ukrainian Special Forces soldier strolled back and forth, chatting with the receptionist and dipping repeatedly into a bowl of free snacks. But German police were already closing in on him.

After a painstaking investigation, they had concluded that Serhii K had commanded Europe's biggest act of sabotage in decades: a series of explosions in September 2022 deep beneath the Baltic Sea that ripped through the giant Nord Stream pipelines and ruptured the supply of Russian gas to Germany.

After his extradition to Germany and months in isolation in a high security prison, Serhii K will go on trial in Hamburg, next week. He is charged with causing an explosion and a war crime – attacking civilian infrastructure – allegedly acting on behalf of "state agencies of Ukraine". Both he and his country have denied any involvement.

It was 02: 03 am on 26 September 2022 when the first blast severed part of the Nord Stream pipelines, sending vast quantities of gas gushing through the surface of the Baltic Sea.

There were two further explosions targeting both Nord Stream 2 – not yet in action, but already full – and the original Nord Stream 1 that had supplied around half of Germany's annual demand for natural gas. Both have been inoperable ever since.

They "strongly suspect" that Serhii K led a crew that included four deep-sea divers, using a rented yacht called Andromeda.

Once their complex, dangerous mission was done, the saboteurs slipped back into Ukraine unaware of the DNA evidence some had allegedly left on the boat.

As word of the blasts spread, experts and some governments initially rushed to the same conclusion: they blamed Moscow.

After all, and of using its energy supplies for political pressure, russia had a history of hybrid attacks.

But as the airwaves filled with commentators citing "suspicious" Russian naval activity near the blast site, German police ignored the noise. They went on after the forensic crumbs. Eventually they led to Ukraine.

Notably, the case since built by investigators alleges that Serhii K entered Germany for the Nord Stream attack on a forged passport, probable issued by Ukraine's security services.

In the extradition files sent to Italy he is named as Serhii Kulinich.

That might explain why he looked so calm on his holiday in Italy.

He had been travelling widely, and without incident, for the past year. In a copy of his real passport seen by the BBC there are more than two dozen stamps from countries including France, Spain and Canada – all dated after the Nord Stream attacks.

Italian police say the actual arrest warrant was only issued on 18 August after he had travelled south and left Poland, suggesting the Germans were not sure their neighbours would co-operate and detain him.

By the time his wife created a booking at La Pescaccia though, he was officially a "wanted" man. As shortly as he demonstrated his passport at check-in at the resort, the local carabinieri obtained an automatic alert.

Police arrived to create their arrest late that night, leading Serhii K away from the glamping site and his family in handcuffs.

None of the Nord Stream suspects have spoken publicly and no-one admits any role in the explosions.

But I have talked to some of the Ukrainians caught up in the case, and individuals close to them.

"Anyone who admits involvement in this mission, they're immediately a target for Russia, " one source explained. "Whoever did it can never confirm that."

Nord Stream was a major investment and worth major capital to Moscow in fuel sales. But it additionally produced Germany and others dependent, giving Russia immense leverage over Europe.

That is why Ukraine, the US and Poland in particular all loathed it.

Another source I spoke to was "eaten alive by anxiety" over the investigation and baffled that Germany, a close ally of Ukraine, was even pursuing prosecution.

"Many Ukrainians believe that these pipelines, they helped Russia to fight so blowing them up was a good thing for our country, " they pointed out.

For context, the German prosecutor's office informed me the justice system was outside of any politics. Sabotage is an offence against Germany's constitution.

Equally frustrating for the Ukrainians I met was their own government's silence.

"At the very minimum, he's a military man, so if there are any questions, they should be addressed to the state, not to him, " a close contact of Serhii K complained.

Ahead of his extradition to Germany, his lawyer here in Italy informed me his client had felt "abandoned".

Germany has a whole list of suspects, but only one other name has been made public so far.

Volodymyr Zhuravlyov is at present fighting extradition from Croatia where he was arrested in August.

Though he denies any role in the real-life operation, he was there as a consultant on a new thriller film regarding the Nord Stream blasts.

When he knew Germany was pursuing him, travelling was a risky move.

Zhuravylov has lived in Warsaw with his family since just before Russia's full-scale invasion of Ukraine and has his own business there installing air conditioning. He is additionally a keen and competent deep-sea diver. But he is a civilian.

Last year, he was arrested in Warsaw on a warrant issued by Germany but a Polish judge refused to extradite him.

In a dramatic twist, he ruled instead that a Ukrainian attack on Nord Stream, if that was what happened, would be a "just" act in a "bloody and genocidal war".

Taken together, the developments around nord Stream trial: How German police followed the evidence point to a situation that is still moving, and the coming days should bring more clarity.