Early on Saturday morning, a team of Russian secret service agents honed in on their target – an elderly scientist working at the mechanical engineering research institute (TsNIIMash) in Korolev, a satellite town not far from Moscow.

Viktor Kudryavtsev, 74, was in bed when officers arrested him. He was hardly in the best of health. He suffers from diabetes, several other age-related conditions, and had only recently recovered from a heart attack.

As a result, the hours that ensued were a test of endurance. He was delivered first to a secret court; and then to Moscow’s infamous Lefortovo prison, where he was stripped of his civilian clothes and given a black uniform to wear.

Over the weekend, reports in the local press gradually alerted the outside world to his story.

First, the state news agency Tass reported the arrest of a “decorated” scientist. Hour by hour, the details were filled in. The scientist’s alleged area of expertise – hypersonic missiles. The alleged crime – leaking secrets to a “Nato country”. The year – 2013. The fact of ongoing searches at his institute. And the article under which the scientist was being tried – 275, or state treason.

The human rights worker Yevgeny Yenikeyev found out about Mr Kudryavtsev’s detention by accident. He was in Lefortovo prison the day of the arrest, visiting Antonina Zimina, another Russian recently arrested for crimes against the state. On leaving the meeting, Mr Yenikeyev casually asked prison guards if there was anyone else he should see.

He was granted access to the new prisoner. Mr Yenikeyev recalls seeing a “tired, sad” man. He was allowed to give his age, where he lived, and the article under which he was being tried. But there would be no answers to questions about where the man worked. That information was secret, prison officers said.

The deal for human rights workers allowed into Russian prisons is simple enough: Don’t ask too many questions. So instead, Mr Yenikeyev focused on the basic day-to-day things that are important to someone in prison for the first time.

“We talked about how to write a letter to family. How to buy things from the prison shop. That kind of thing. He didn’t ask about much other than his wife. We didn’t talk about his case,” he says, speaking to The Independent.

But information about Mr Kudryavtsev’s workplace and history was easily available on open sources.

We talked about how to write a letter to family. How to buy things from the prison shop. That kind of thing. He didn’t ask about much other than his wife. We didn’t talk about his case Yevgeny Yenikeyev, human rights activist

Snippets of his biography are listed on the website of his research institute. For example: the scientist was awarded a government prize in 2004 for a “rocket and space complex” called “Sea Launch”. He is also listed as a deputy head of a department. A look at academic citations reveals him to be the author of dozens of papers: from rocket aerodynamics to thermal characteristics of manufacturing materials.

According to the Kommersant newspaper, Mr Kudryavtsev was arrested in connection to his work developing materials used for new hypersonic missile systems.

That technology is at the heart of several “new generation systems” unveiled by President Vladimir Putin during his 1 March state of the nation speech. Kommersant makes mention of the “kinzhal” missile system, which Mr Putin has claimed is able to circumvent any existing missile shield.

“Even a cleaner at one of these institutes would be interesting for a foreign state,” says Gennady Gudkov, an opposition politician who worked in the KGB’s counterespionage section between 1982 and 1993. “Mr Kudryavtsev, who has access to a broad range of military developments, would be a remarkably useful asset to someone.”

Carter Page denies that Russians were trying to recruit him

Yet the case is strange, says Mr Gudkov. Had this been a counter-espionage operation of the type he had professional experience of, things would have played out differently.

There would be evidence of secret notes, and secret communications devices – like, perhaps, the “British rock” found in a Moscow park in 2006. There would be links to foreign embassies, with individual diplomats labelled as persona non grata and deported.

During Soviet times, this was a standard protocol that happened time and time again.

Here, the evidence is missing, says Mr Gudkov: “You have none of the usual tell-tale signs of espionage. There is no motive, no link to a foreign handler, no secret communication, no sense of a reward – whether that be cash or promise of asylum, no regular meetings. That is all highly suspect.”

Mr Gudkov said he could not rule the scientist “accidentally” leaking a state secret – in other words, without the normal signs of espionage. After all, security services have been known to go after scientists who have quoted material already in the public domain, he says.

But if this was the case, another article of the criminal code would have been applied, most likely 283, “revealing a state secret”. Instead, Mr Kudryavstev is being tried on the most serious of articles – 275, or “treason”.

You have none of the usual tell-tale signs of espionage. There is no motive, no link to a foreign handler, no secret communication, no sense of a reward — whether that be cash or promise of asylum, no regular meetings. That is all highly suspect Gennady Gudkov, opposition politician and former KGB member

Pavel Luzin, a specialist in the space and defence industry at Perm State University, is similarly unconvinced of the scientist’s crime. He says the case resembles other processes against elderly researchers who were tried and imprisoned on flimsy evidence.

Mr Kudryavtsev was a “scientist of the Soviet school”, says Mr Luzin. He had the chance to leave and make money two decades ago; having remained in science, he “wasn’t about to begin selling secrets now”.

Instead, the scientist was likely to have been chosen as a “scapegoat” by security officers looking to impress senior officers. Perhaps the aim was to instal a regime of fear in the scientific community, he says: “The Kremlin is very keen the truth about kinzhals doesn’t get out, for example, because they don’t actually exist as advertised.”

Welcome to the real Russia, on eve of election Show all 29 1 /29 Welcome to the real Russia, on eve of election Welcome to the real Russia, on eve of election St Petersburg, Moscow Station Russia's imperial capital is the starting point of our journey Dmitry Markov Welcome to the real Russia, on eve of election Chudovo market Chudovo was one of the first stops of Radishchev's journey Welcome to the real Russia, on eve of election Chudovo market "They say the fish rot from the head down" Welcome to the real Russia, on eve of election On the way out of Chudovo Russia election eve For Ollie Carroll feature Welcome to the real Russia, on eve of election Polling station "We choose our president, we choose our future" Dmitry Markov Welcome to the real Russia, on eve of election Sergei Mikhailov "People have become fussy and want clear water" Dmitry Markov Welcome to the real Russia, on eve of election Radishchevo village "Life is just great" Dmitry Markov Welcome to the real Russia, on eve of election Veliky Novgorod Once the seat of a forward-looking republic — Russia's first experiment with democracy Dmitry Markov Welcome to the real Russia, on eve of election Veliky Novgorod Once the seat of a forward-looking republic — Russia's first experiment with democracy Dmitry Markov Welcome to the real Russia, on eve of election Veliky Novgorod Once the seat of a forward-looking republic — Russia's first experiment with democracy Dmitry Markov Welcome to the real Russia, on eve of election Veliky Novgorod Russia election eve For Ollie Carroll feature Dmitry Markov Welcome to the real Russia, on eve of election Navalny HQ Navalny's activists continue campaign despite their leader being barred from the elections Dmitry Markov Welcome to the real Russia, on eve of election Navalny HQ Fake election newspaper "Putin's Pravda" Dmitry Markov Welcome to the real Russia, on eve of election Roadside cafe, Proletary, Novgorod Oblast "Thatcher was a bitch, but I liked her. This one is just a bitch" Dmitry Markov Welcome to the real Russia, on eve of election Service station, Valdai Propaganda — keeping pace every step of the way Dmitry Markov Welcome to the real Russia, on eve of election Trucker's cafe, Yedrovo Two years ago, truckers staged a protest against new road taxes. Today, many of them are choosing to stay away from the elections Dmitry Markov Welcome to the real Russia, on eve of election Trucker's cafe, Yedrovo Two years ago, truckers staged a protest against new road taxes. Today, many of them are choosing to stay away from the elections Dmitry Markov Welcome to the real Russia, on eve of election Trucker's cafe, Yedrovo Two years ago, truckers staged a protest against new road taxes. Today, many of them are choosing to stay away from the elections Dmitry Markov Welcome to the real Russia, on eve of election Some roads lead to Moscow Russia election eve For Ollie Carroll feature Credit: Dmitry Markov Dmitry Markov Welcome to the real Russia, on eve of election Along the road to Vyshny Volochyok Mikhail, an Afghan veteran, is proud of his mushrooms Dmitry Markov Welcome to the real Russia, on eve of election Along the road to Vyshny Volochyok Pensioners are the group most likely to vote on Sunday — and most of them for Vladimir Putin Dmitry Markov Welcome to the real Russia, on eve of election Vyshny Volochyok The Soviet Union is still viewed by many as a golden era — with social welfare and stability Dmitry Markov Welcome to the real Russia, on eve of election Nelle's Shop, Tver "People have cut back on the fags, but you won't see them turning away from alcohol — they'd sooner steal it than go without" Dmitry Markov Welcome to the real Russia, on eve of election Polling Station, Tver Russia election eve For Ollie Carroll feature Dmitry Markov Welcome to the real Russia, on eve of election Car scrapyard, Tver Peace to the world! Dmitry Markov Welcome to the real Russia, on eve of election Proletarian Courtyard, Tver Rats, black mould and communal living Dmitry Markov Welcome to the real Russia, on eve of election Proletarian Courtyard, Tver Rats, black mould and communal living Dmitry Markov Welcome to the real Russia, on eve of election Proletarian Courtyard, Tver Rats, black mould and communal living Dmitry Markov Welcome to the real Russia, on eve of election Grandma Masha "Help me! I’ll get on my knees to beg you" Dmitry Markov

Another factor that could be playing a role is a massive reorganisation under way in the Korolev institute’s parent organisation, Roscosmos. In June, Alexei Kudrin, the head of the Public Accounts Chamber, and close Putin confidence, accused Roscosmos of misspending at least 760bn roubles of public money in 2017. Perhaps, speculates Mr Gudkov, the FSB wanted to show their strength in order to to have a say in the reorganisation.

None of this, of course, is likely to help Mr Kudryavtsev as he begins to get used to life behind bars.