Others suffered electric shocks to their genitals and ears, were beaten up and suffocated by various methods, victims told law enforcement.
Prisoners were stuffed in overcrowded cells in Kherson, Ukraine, without sanitation or sufficient food or water for up to two months.
Some were also blindfolded and bound, had severe bruising and broken bones and suffered sexual violence including forced nudity, accounts said.
And physical assaults were particularly brutal on men, sometimes lasting for hours, one detainee said.
Russia captured Kherson in March, about a month after it launched war against Ukraine. It then withdrew in November.
Oksana Minenko, 44, claimed she was repeatedly detained and tortured by Russian soldiers. The accountant said: “One pain grew into another. I was a living corpse.”
Troops put her hands in boiling water, ripped off her finger nails and smashed her face with rifle butts so badly she needed plastic surgery, she claimed.
Men also forced her to undress then beat her while her hands were tied to a chair and her head was covered.
She said: “When you have a bag on your head and you’re being beaten, there is such a vacuum, you cannot breathe, you cannot do anything, you cannot defend yourself.”
Minenko reckons she was targeted because her husband was a Ukrainian soldier. He died defending Kherson’s Antonivskyi bridge on the first day of full-scale war.
Troops turned up at his burial and made her kneel next to his grave, firing their guns in mock execution, she claimed.
Men in Russian military uniforms and balaclavas subsequently turned up at her home on three occasions at night in March and April to interrogate her and take her into detention.
Olha, 26, says she was beaten, given electric shocks and subjected to forced nudity and torture by Russian forces.
Meanwhile, Andrii, 35, said he was beaten, forced to undress and had his genitals and ears electric shocked over five days.
He said: “It’s like a ball flying into your head and you pass out.”
His captors interrogated him over weapons and explosives storage, he said, because they thought he was linked to a resistance movement.
And Liudmyla Shumkova, 47, said she spent 54 days in captivity with her sister.
The health lawyer said the Russians asked them about her sister’s son because they believed he was involved in the resistance movement.
Around six people were packed into a cell with just a small window for light and just one meal a day, she said.
While she was not physically assaulted, others including a female police officer were.
Men received particularly harsh torture, she said, adding: “They screamed. It was constant, every say. It could last for two or three hours.”
At least ten sites in the region are said to have been used for unlawful detentions where around 200 people were allegedly tortured or assaulted.
Another 400 people were held there illegally, it is claimed. The figures are expected to grow as the investigation continues.
Kherson’s chief war crimes prosecutor said the torture “was done systematically, exhaustingly” to obtain information about Ukraine’s military.
In one office building, inscriptions on a wall read “pray to God for us”, “God, give us strength” and “Lord keep us safe”.
Tallies were also on the wall, possibly counting the number of days they were in captivity.
Broken chairs and plastic ties used for torture were found in the basement there, along with human excrement. An LGBT+ flag was in the building too.
More than 7,700 reported war crimes have come from Kherson. Ukrainian authorities have reports of more than 50,000 in total.
Moscow has denied committing war crimes or targeting civilians despite overwhelming evidence.
Russia instead accused Ukraine of war crimes and the West of ignoring them.
The Sun joined Ukraine’s special forces hunting Russian stragglers in Kherson last year, as rockets and mortars pounded the city.