The convoy snaked through Ukraine’s north-eastern Sumy region on a bitter February morning.

A police car led the way, followed by a unit of forensic officials and a refrigerated van containing the corpses of dozens of Russian soldiers.

The delegation was travelling into Russian territory for one of the only functioning levels of diplomacy between Kyiv and Moscow: the exchange of dead bodies from either side.

As the cars moved through the villages approaching the border, traffic stopped to make way.

A young boy stood in the road and waved. This same route is used to collect Ukrainian prisoners of war from Russian territory, and locals line the streets to greet their returning fighters.

“He thinks we’re going to collect prisoners of war,” said Vitaliy Matvienko of Ukrainian military intelligence.

But once in Russian territory this convoy would begin a more sombre task: passing over its load of dead bodies, then filling up with those of Ukrainian soldiers.

The Telegraph observed the convoy travelling into Russian territory but did not cross the border.

Though a ceasefire is enacted for the duration of the exchange – which takes less than an hour –  the process is nevertheless tense.

The border road must be de-mined to let the vans pass and mined again once they return.

Russian forces regularly shell the area and snipers hide in the trees on the edge of the fields observing the exchange.

At the border, forensic scientists from the International Committee of the Red Cross carried out a spot check on the bodies.

The corpse-carrying vans then crossed into Russian territory to meet their counterparts, with Ukrainian rescue workers, members of Ukraine’s security services and representatives from the ICRC in tow.

“We go to their side because we don’t want Russian vehicles on our territory,” said Mr Matvienko. “It’s a risk, of course, but it’s a lower risk than if they came here.”

The repatriation of dead Ukrainian soldiers from areas now occupied by Russia is part of a huge effort by several Ukrainian state agencies to find and identify some of the 24,000-plus registered missing Ukrainian soldiers and thereby give some closure to their loved ones.

In total, 2,495 bodies of Ukrainian soldiers have been returned through these exchanges, said General Dmytro Usov, head of Ukraine’s co-ordination centre, which oversees the bodies corridor.

“This corridor is the only way to return our fallen home,” said Mr Usov. “It [not only] means that all the dead will be decently buried in Ukraine [but also] that their relatives, and all the caring citizens of our country, will be able to pay their respects.”

The bodies themselves are recovered by the soldiers on either side – often at great risk, in heavily mined areas or from the no-man’s lands between the two frontlines. Several soldiers have been injured and killed trying to retrieve their dead comrades.

At the meeting of the two sides, Ukraine’s security services – who travel unarmed in ICRC vehicles as part of the conditions – exchange lists of identifying marks of Russian soldiers and, when documented, their names. At the same time the rescue workers from either side unload and load the dead.

“The ICRC’s presence at the exchange is designed as a signal of the security for both parties,” said Jürg Eglin, head of ICRC operations in Ukraine, at the exchange.

Under the Geneva Conventions dead bodies and prisoners of war are meant to be exchanged only after the war. But in the Russia-Ukraine war, exchanges of both started in earnest after the first six months.

In summer 2022, the ICRC, which has offices on both sides, connected the two states to discuss bodies that ended up on the wrong side. They then helped to put together the corridor, said Oleh Kotenko, who headed body exchanges at the time.

“The Russians rang me and started to say how they were going to bury our guys in certain places in Russia and I said why? Let’s just exchange,” said Mr Kotenko.

As the convoy returned from the border, word had spread that it was carrying fallen soldiers and villagers came out to pay their respects.

Families kneeled together on the snow and the elderly stood at the gates of their houses, hands clasped. Many were red-faced and weeping.

So far, the body exchanges, unlike the prisoner-of-war trades, have continued without disruption. But once the bodies are back in Ukraine, the identification process can take anywhere from 10 days to a year, or more, say officials.

Maksym Fedorenko, head of the Cherkasy region morgue, one of several morgues that deal with the repatriated bodies, said the hold-up is usually caused by the state of the bodies and the collection of DNA samples from relatives.

Cause of death

Most of the repatriated bodies are unrecognisable: charred, rotten and disfigured by explosives.

After the bodies are exchanged – between 60 and 100 soldiers at one time – they travel straight to a morgue for processing. The mortician and investigators note any physical identifiers, take pictures, extract DNA, compile a dental card and establish the cause of death.

The few whose documents survived or are physically well-preserved are prioritised.

Given the time needed to defrost a body and the morgue’s ability to examine three to four bodies per day, a single repatriation load takes the morgue at least a month to six weeks to process.

Once a body is processed, bits of skin, hair or tissue are sent for DNA extraction at state laboratories – a process which takes around four days. DNA certification is an obligatory part of the identification process for all dead soldiers under Ukrainian law.

But the state of the repatriated bodies means DNA samples are often of poor quality and sometimes impossible to obtain. If the first sample doesn’t generate enough data, lab clinicians may either take a different part of the sample for testing or request additional samples from the morgue. The bodies then need to be defrosted once more, another sample obtained and the lab work starts afresh.

“The main thing is not to make a mistake,” said Vasyl Aksyonov, who heads the DNA testing under Cherkasy’s police on why the procedure cannot be speeded up.

Acute staff shortages

The other issue is the relatives’ DNA samples. When relatives are notified that the soldier is missing in action, they are encouraged to give DNA samples – a system which has improved since the early stages of the war but is nevertheless imperfect. There are acute staff shortages in some labs and at a local police level, swabs can be incorrectly taken, say officials.

Kostyantyn Dubonos, deputy head of Ukraine’s state forensics bureau, said Ukraine has trained 1,500 lab clinicians and opened 13 laboratories since the invasion and plan to open a further five this year. Increasing capacity, he said, will mean that relatives will hear sooner.

“The work has increased year on year by 90 per cent,” Dubonos said. “Even if the war ends now, with repatriations and discoveries, we will have enough work for a decade to come.”

But another factor slowing the process, and out of the control of the authorities, is that some relatives refuse to give DNA samples, wanting to believe that their loved ones are alive and being held prisoner. Even relatives of those who have been identified and buried have come back asking for additional DNA tests, said Dubonos.

Mykola Shatniuk, a 33-year-old soldier from Ukraine’s 72 Brigade, was killed in Volnovakha, Donetsk region in late October 2022 and exchanged through the corridor just over a month later in early December 2022. But his body was not released to his family until six months later, in July 2023.

His wife, Alina, who had been his childhood sweetheart since age 13, united with the wives of 25 men from Mykola’s unit who also went missing that day to find her husband.

For six months, Alina, together with the other wives, scoured Russian prisoner of war posts and pushed for news through every possible avenue in Ukraine and international organisations as well as relatives in Russia.

Lack of laboratories

Then in late April, she was notified of a possible DNA match. Her husband’s brother had submitted the first sample and she was asked to submit a sample from her son to be certain. At the time, the lack of laboratories in Ukraine and the blackouts meant two samples could not be processed at one time. “When they said there was a match: That was it. I screamed, I cried,” said Alina.

Two months later, the second DNA sample came back as a definite match and Mykola’s body was released and buried.

While part of the issue was the length of time, the other was that Mykola’s fellow fighters and their commander declined to tell the wives what happened so they hoped they might still be alive. “They couldn’t say he died because where’s the body?” she recalled. Only once the body was released was she told how her husband’s position was surrounded when heavy equipment was relocated for the Kherson counteroffensive.

Mykola had been a contractor in the army on and off since 2014. For the first two months of the war, he was stationed in Kyiv region. But in May 2022, he volunteered to serve at a so-called zero-line in Donetsk region.

“He didn’t tell me that he was going to the zero-line because he knew I would have tied him up here,” said Alina. “He was like a rock for me… and he was brave, not afraid of anything.”

Mykola had tried to prepare Alina for the eventuality of his death, she said, sending her numbers of people she could call and telling her to take her driving test.

Mykola received a medal for bravery for his service in December. He is survived by his two children, 14-year-old Ania and four-year-old Ignat, who is a “copy” of his father, according to Alina. When Alina asks Ignat who his father was, he cries out “A hero!”

The wives of the 25 men have agreed to hold a memorial service at the location where their husbands were surrounded when the area is de-occupied, said Alina.

“I thank God that he has returned the body, that we have it,” she said. “We know that it is necessary to go to church already to gain peace, and not to look for him among the living [prisoners of war]. But equally, I don’t believe it, I don’t want to believe that it is true.”