They drove a Kia and paid their taxes every year - neighbors had no idea they were elite foreign spies

A 'quiet' couple who led a humdrum life in a sleepy suburb left friends speechless after it emerged that they were senior Russian spies operating a network of European informants for Vladimir Putin.

Ludwig Gisch would cycle to his IT start-up every day from the pastel-colored house he shared with wife Maria and their two young children on the outskirts of Slovenia's capital Ljubljana.

She ran an online art gallery, sent her children to the city's British International School, and was described by one neighbor as a 'gray mouse'.

In reality, he was Artem Viktorovich Dultsev and she was Anna Dultseva of Russia's foreign intelligence service the SVR, tasked with undermining Western energy security after Putin's invasion of Ukraine and she was his boss.

'Now we will see how important these people really are to Russia,' one official told the Guardian. 'This is big game now; it's clear that Slovenia is just a proxy here.'

Ludwig Gisch and his wife Maria Rosa Mayer Muños were in reality Russian spies Artem Viktorovich Dultsev, and Anna Valerevna Dultseva 

Dultseva (pictured) ran an online gallery and used exhibitions across Europe as cover  

The couple had spent a decade scrupulously establishing their cover stories in an effort to evade detection, arriving in Argentina on tourist visas in 2012, getting married, and leaving five years later as citizens.

'They were very polite, respectful,' Jamoneria del Virrey, the owner of a Buenos Aires Deli told the WSJ. 'They always paid in cash.'

Moving to Slovenia in 2017 they behaved as model citizens, paying their taxes on time, 'keeping to themselves' and never even collecting a parking ticket for the white Kia Ceed sedan they drove.

But a dawn raid on their Llubjana home in 2022 found hundreds of thousands of crisp Euros hidden in a secret compartment and communications software so heavily encrypted that US intelligence has yet to decode their messages to Moscow.

Viktorovich set up a LinkedIn profile and an online IT business called DSM&IT, offering cloud hosting services, and dutifully filed tax on its reported €43,785 revenues in 2021.

Friends who downloaded its software said it was in marked contrast to the state-of-the-art Moscow communication link.

'I was not very impressed,' said one. 'It was five years behind current technology in Europe or even anything made in Russia.'

Maria, real name Anna Dultseva, made a better showing of her online gallery Art Gallery 5'14', posting photos from exhibitions across Europe, but usually careful not to be photographed herself.

'She was always in a good mood and joyful, and had lots of fun together with other artists,' said Croatian photographer Marko Milić who met her at a Zagreb art fair.

The suburban house on the outskirts of the Slovenian capital Ljubljana where the couple lived with their two children while spying for Russia

The pair spent ten years constructing their elaborate false identity including five in Argentina 

The pair had a wedding in Argentina despite having been previously married in Russia

The couple spoke both English and German with people who met them.

They claimed to find Slovenian too difficult to pronounce, although investigators have suggested they were worried about their Russian accents coming out in a fellow Slavic language.

At home the couple would speak Spanish to their children, according to a neighbor who would occasionally see them in the garden.

'I speak Spanish well and I could tell she didn't have an accent in Spanish. They were ordinary nice people, there is no way they were spies. I think it's all invented by the media,' said the neighbor.

From their base in Slovenia they were able to travel visa-free across the European Union developing sources, recruiting informers, and liaising with other agents.

After 10 years of establishing their new identities it was Russia's invasion of Ukraine in February 2022 that led to their activation.

They began targeting the EU's Agency for the Cooperation of Energy Regulators (ACER), based just five miles away from their Llubjana home.

'They had been awoken,' said Vojko Volk, Slovenia's state secretary for international affairs and national and international security.

Russia supplied just under half of Europe's gas on the eve of the invasion, earning billions of dollars in foreign currency from it.

But Europe's politicians were under extreme pressure to slash their dependence on Russian energy and Moscow was desperate for intelligence from ACER.

The case has sparked comparisons with the Emmy award winning spy drama The Americans 

Its two spies were back in Buenos Aires getting their fraudulently obtained passports renewed as the war broke out but were soon back in Slovenia attempting to penetrate ACER.

But as relations with Russia deteriorated, Slovenia's own spy agency received a tip-off about the 'normal' and 'quiet' couple living in the pleasant Črnuče suburb of their capital.

Wiretaps and text messages revealed suspicious meetings across Europe and the Slovenians called in allied intelligence agencies to piece together the couple's history.

'We worked together in the utmost secrecy,' Volk told the WSJ. 'It was a puzzle.'

They discovered that the couple's companies were kept afloat by cash from their bosses in Moscow, while investigators in Argentina found that the only two witnesses at their wedding had given false identities.

Immigration officials in Buenos Aires then ran the couple's fingerprints through the Interpol database and discovered they were those of Artem Dultsev and Anna Dultseva.

Their sudden arrest in December 2022 sparked a dash back to Moscow from spies fearing exposure.

A woman in Rio De Janeiro and a man in Athens were stunned to find that their partners were married Russian spies, one of which had created her cover by stealing the identity of a Greek baby who died in 1991.

The veterinarian girlfriend of Campos Wittich helped mobilize the campaign to find him when he disappeared during a holiday in Malaysia, only to discover that he was already married to his fellow Russian spy Irina Romanova who disappeared from Athens at the same time.

Seized in December 2022 they have been held in a Slovenian prison awaiting trial since then while their son and daughter, aged eight and 11 have been placed with foster carers.

'They have taken it stoically. It's obvious they are pros. But they are not talking,' a source said.

Moscow has been increasingly relying on unknown agents for its intelligence gathering since the expulsion of more than 700 diplomats in the wake of its war in Ukraine.

'Illegals are again growing in significance for Moscow, especially as the line between espionage and war is becoming almost nonexistent,' Russian security expert Andrei Soldatov told the WSJ.

Many have targeted the US including the 10 uncovered by the FBI operation Ghost Stories in 2010.

Suspected Russian spy Campos Wittich fled to Moscow in the wake of the Slovenian arrests, leaving a distraught girlfriend in Rio De Janeiro 

Wittich is married to fellow Russian spy Irina Romanova who also left an unsuspecting partner when she fled Greece 

They bought houses, took jobs and raised families in a bid to lull suspicious neighbors.

One studied at Harvard, two at Seton Hall University, and one became the in-house IT chief of a well-connected DC consulting firm.

The revelations inspired the 2013 drama series The Americans based on married KGB agents spying for the Soviet Union after moving to a DC suburb.

The couple face a maximum of eight years in prison for espionage under Slovenian law and there is speculation they may be traded for Western prisoners held in Russian jails.

'We know they were important, serious agents,' Volk said.

'It's like 'The Americans,' except in Slovenia.'