But instead of facing their day in court on possible murder charges, the five former members of the once dreaded but now disbanded Berkut were set free on December 29.

They were among the 200 prisoners freed in a swap between the Ukrainian authorities and the Russia-backed separatists who hold parts of two eastern provinces -- an exchange that on the whole was widely hailed not only by relatives of those released but the international community as well.

The swap at a checkpoint near the separatist-held city of Horlivka was part of an agreement brokered earlier this month at a summit of the leaders of Ukraine, Russia, Germany, and France.

The hope is it will be a step toward ending the conflict in eastern Ukraine that has killed more than 13,000 people since erupting shortly after Yanukovych fled the country amid the massive protests in Kyiv. In the wake of his ouster, Russia seized the Crimean Peninsula and fomented separatism, helping ignite the war in the Donetsk and Luhansk regions.

German Chancellor Angela Merkel and French President Emmanuel Macron, whose countries are leading efforts to end the conflict in the region known as the Donbas, viewed the exchange as "a long-hoped-for humanitarian gesture that should contribute to the restoration of trust between the two sides," according to a German government statement.

Ukrainian President Volodymyr Zelenskiy has largely staked his presidency on ending the conflict. It was the second such exchange since September and the biggest swap in two years.

According to the Ukrainian Security Service (SBU), the separatists released a total of 76 people, including 12 military personnel, two of whom had been held since 2015 after being ambushed while escorting a convoy of wounded out of the battle of Debaltseve, which destroyed much of the city.

Amid scenes of jubilation, those freed were warmly welcomed by relieved family and friends after touching down at Boryspil Airport near Kyiv late on December 29 along with Zelenskiy, who told reporters, "It's wonderful, I'm so happy."

However, the Ukrainian president also faced questions over whether he may have paid too high a price for their freedom, with many questioning why the five former Berkut officers, in particular, were among the 124 people Kyiv turned over to the separatists.

Zelenskiy suggested it had been a tough choice but insisted his priority had been to return "the living."

"I believe that our fighters, our military, our journalists are all heroes, and I'm sure that the priority for us is to have our people returned. I respect all parents and families who lost their loved ones on the Maidan. Unfortunately, we cannot return those who are no longer with us, but we could return the living, and I'm sure that this is our priority," Zelenskiy said at the airport.

Oleh Sentsov, a filmmaker who was freed from prison in Russia and returned to Ukraine in the September swap, welcomed the fresh prisoner exchange -- but faulted Kyiv for turning over "real murderers" while Ukrainians, including Crimean Tatars, are still being held by Russia on what rights groups say are politically motivated charges. "Crimean Tatars and our other political prisoners will continue to remain in Russian prisons. Innocent. For this, Ukraine will deliver real killers," he wrote on Facebook.

Why Does Russia Want Berkut?

The Berkut, according to Ukrainian investigators, had been responsible for the shooting deaths of dozens of demonstrators at the pro-democracy, anti-corruption Euromaidan protests in early 2014. In particular, the investigation implicated 25 Berkut personnel from the so-called "Black Company", as well as their deputy commander, in the killing of unarmed demonstrators on February 20.

The 48 protesters killed that day, and more than 50 others who died in other violence against demonstrators, are honored as the Heavenly Hundred in Ukraine and seen widely as martyrs.

Of the accused officers of Berkut -- which means Golden Eagle -- 21 fled either to Crimea or Russia, where 15 received citizenship, and three were granted asylum. Russia has rejected all Ukrainian requests to extradite them.

The other five -- Serhiy Tamtura, Oleksandr Marynchenko, Pavlo Abroskin, Serhiy Zinchenko, and Oleh Yanishevskiy -- had been in Kyiv and set to face trial, until December 29.

The European Union said that "we take note" of the exchange of the ex-Berkut officers.

"We expect all accusations will continue to be investigated and the parties concerned to ensure that those responsible are brought to justice," the EU said in a statement.

Some commentators suggested Moscow had insisted on their release to wipe clear any possible trail linking the Kremlin to the deadly crackdown on the Euromaidan protests.

"Russia's insistence on the inclusion of Berkut officers linked to the 2014 Maidan massacre in today's prisoner exchange is interesting. Why would the Kremlin seek the release of Ukrainians accused of killing Ukrainians -- unless the accused (and the killings) were tied to Russia?" the English-language magazine Business Ukraine wondered in a Twitter post.

Others said that by insisting on including the former Interior Ministry soldiers the Kremlin was attempting to undermine Zelenskiy at home.

"I think mainly to make Zelenskiy do something deeply unpopular and unjust, something that will anger some of the most idealistic and active people in the country since 2014. Will also be seen as a big win for his clients in east Ukraine, and further muddy any Maidan investigation," Andrew Roth, Moscow correspondent for The Guardian, wrote on Twitter.

The leader of the separatist-controlled area in the Luhansk region praised the swap as the separatists' "latest victory," according to AFP.

Convicted Killers

The ex-Berkut officers weren't the only controversial figures on the list of detainees released by Kyiv. Three people convicted of a 2015 bombing in Kharkiv that killed four people during a peace march, including a 15-year-old boy, were also in the prisoner exchange.

And it wasn't the first time Zelenskiy has faced questions over those Ukraine has exchanged with the separatists.

Volodymyr Tsemakh -- a "person of interest" in the Dutch-led probe into the July 2014 downing of Malaysia Airlines Flight MH17, which investigators have determined was shot down by a Russian missile brought into separatist-held territory in Ukraine -- was among the 35 prisoners Ukraine handed over to the separatists on September 7.

Zelenskiy said he did everything possible to ensure Tsemakh would be questioned by the Dutch and that the process "was complicated...I was scared that the [prisoner] exchange would fall apart because of that."

All 298 people on board MH17 were killed when it was shot down en route from Amsterdam to Kuala Lampur.

Three Russians and a Ukrainian were indicted over the downing of MH17, and court proceedings in the Netherlands are scheduled for March. But the four suspects most likely to be tried in absentia.

While many of those handed over by Kyiv to the separatists had faced concrete charges, the same cannot be said for many, if not all, of those released by the separatists.

Among the civilians released by the separatists were a pet-shop owner who was detained last year on unspecified charges and a woman from government-controlled territory who was seized while visiting her mother in a separatist-held area.

Viktoria, who did not give her last name, told AFP she had been held by the separatists for three years after being convicted of "state treason."

With reporting by RFE/RL's Ukrainian Service