Alexander’s restless blue eyes speak as loudly as his words.  He is fuming, and justifiably so, as he returns to prison in the recently liberated city of Kherson, where he says Russian guards beat him daily.   

  We pass cell blocks and rusty outdoor exercise cages, move through guard rooms, turnstiles and heavy iron doors and travel along fences piled high with razor wire in this Soviet-era prison until we reach one of the epicenters of the brutal Russian occupation of Ukraine .   

  Here, in a dark and rubble-strewn hallway, Oleksander and another former prisoner who did not want to be interviewed say Russian guards have executed Ukrainian prisoners for pro-Ukrainian chants or tattoos.  CNN is identifying Oleksander only by his first name for security reasons.   

  As Alexander pushes open a solid red iron door at the end of the corridor, burning wood falls from the ceiling, smoke billows and glowing embers fall out.  The ceiling in this section of the beehive block is on fire and the burning wood is collapsing.   

  That’s where Russian troops brought people for torture, Oleksander tells us.  After the departure of the Russians from Kherson they “set fire.” [to] to destroy the evidence of their crimes,” he says.  It is impossible to enter to check it because of the flames.   

  The Russian retreat was swift – some 30,000 troops, according to Russia’s defense ministry, withdrew within three days of Russia announcing they were pulling out.  They had been preparing for the move for several weeks and blamed poor supply lines on the Dnipro River, which Ukraine had been deliberately targeting with US HIMARS missile launchers since late July.   

  In daylight outside the cell, Oleksander says he was arrested in his apartment by the Russian police, accused of being a criminal.  He says they deliberately broke his leg by kneeling on him while restraining him.   

  He tells us that it was not his first time in Kherson prison, having previously spent time there for a criminal offence.  But unlike the Ukrainian guards, he says, the Russians were needlessly brutal.  “They abused everyone, kept us hungry, used us as free labor to repair their military vehicles, beat us as they wanted,” says Oleksander.   

  Russia has previously denied allegations of war crimes and claimed its forces do not target civilians, despite extensive evidence gathered by international human rights experts, criminal investigators and international media in multiple locations.   

  Kostas’ experience was different – ​​his alleged abuse was more psychological than physical, although he says he experienced enough of it.   

  The Russians suspected him of being part of an underground network of saboteurs targeting officials and their facilities, says Costa, who CNN is identifying only by his first name for security reasons.   

  Mysterious car bombings and other explosions had become a concern for the Russian-installed local administration, whose boss, Kirill Stremousov, died in a sudden, unexplained car accident during the final days of Russian occupation.   

  Shortly after underground activists blew up a Russian police vehicle near Costa’s apartment in Kherson, he says 11 heavily armed Russians showed up at his door and forced their way in.   

  Closer to 30 than 20, Kostas doesn’t let us show his face on camera.  He says the Russians have him in a database and knew details of his mobile phones when they showed up at his flat.   

  They were so well prepared, they knew where he went to school, Kostas says, and accused him of previously being a member of “Right Sector,” a far-right nationalist organization with political and military wings.  He denies belonging to the organization.   

  When we meet in the main square of the city of Kherson amid the cacophony of the liberation celebrations, Kostas is less happy than the others around him.  He says he is taking some time to adjust to the new freedoms and is wary that Russian associates, who are still at large, could target him.   

  Many Ukrainians who came to speak with us in the first days of the liberation told us of their surprise at how many people knew they had collaborated with the Russians when they first took control of the city in early March.   

  A sprightly 71-year-old former marine engineer who came to talk to us a few hours after the Russians left was particularly enthusiastic about the subject.  “A lot of people who were born here, studied here, worked here, welcomed the Orks (an anti-Russian slur), I was surprised, I hated it,” said the man, who did not give his name.   

  The reasons for such cooperation vary.  Conversations with people in the city suggest that a minority were pro-Russian and believed that the Russians would be there to stay, making cooperation the way to an easier life.  others were forced by the Russians to cooperate.   

  Unlike Costa, the former engineer was less worried about the reappearance of those working with the Russians and more worried that they would be held accountable.  “I want to say burn these people who collaborated with foreign powers in hell,” he said.   

  On any other occasion, Kostas looks like the kind of guy who can handle himself – shrewd and, judging by his handshake, strong – but he says the Russians put him in a psychological mess.   

  It started, he said, when he was still inside the apartment when the Russians first detained him.  “A guy came up to me with a gun, a gun to my head and started asking questions.  You know something [will] is it happening to your wife?  If you don’t tell us the truth?  I say ok, I guess I’ll tell everybody, just start asking questions.  They say no, you’ll tell us without question.”   

  This was only the beginning, says Kostas.  When he was taken to a police station and put in a cell, the mental torture got worse.  “There’s nothing that can prepare you for it,” he says.   

  They put a gun to his head again, he says, and told him to talk – again, no questions asked, to increase the pressure to talk – and pulled the trigger.  The emotions are etched deeper on Kostas’ face as he explains the torture.  “I am not sure that all life passes[ed] before my eyes, but it was really scary,” he says.   

  Costa does not claim to be part of this resistance that was organized in part by the Ukrainian intelligence service, or SBU, but many people in Kherson helped where they could.  A hotel owner told CNN that he had been hiding wounded Ukrainian soldiers in his basement for several months until they were smuggled to safety.   

  The Russian hold on Kherson depended on the eradication of pro-Ukrainian sentiment.  Kostas knew that if he couldn’t convince the Russians that he was innocent, they would take him deeper into Russian-controlled territory for more interrogation.   

  After the mock execution, he says, they tried fake electric shocks.  “They put the electricity in my testicles… but they don’t turn on the power.”   

  He said he had prepared himself to snap if the torture got too physical.  “I understand [with] true torture no one can bear,” he says.  Indeed, in the cells below his, he says he could hear people screaming and crying for their mothers as they were beaten into confessing.   

  Through it all he didn’t break, and, without hard evidence, he says, the Russians let him go – but he still finds himself looking over his shoulder.   

  Kostas may feel some relief in the coming weeks.  a Ukrainian reconnaissance commander CNN met months ago during the push for Kherson, arrived in the city Monday with a stated mission: root out residents who had collaborated with the Russians.   

  How the Ukrainian military handles these suspects will be a true measure of how much they want to separate themselves from the Russian-style brutality Kherson has endured for most of 2022.