Ruslan Vakhapov recognised all the prison guards on trial last month for the brutal torture of an inmate in a Yaroslavl prison. They used to be his jailers too.

Now free, the former inmate has turned activist, and said he had come to report from one of Russia’s most important prison torture cases in the past decade.

His testimony to the Public Verdict Foundation, a Russian human rights NGO, about the brutality meted out inside the prison was later backed up by a 10-minute video of an inmate, Evgeny Makarov, being slowly beaten unconsciousness.

“I know all these men, I know them all well,” Vakhapov said in a phone interview from Yaroslav, where he is following, as a representative of Public Verdict, the trial of those accused of beating Makarov. “Who did what, who beats prisoners, who doesn’t. During five and a half years inside, you learn these things.”

Vakhapov had already made a name for himself as a whistleblower against rough treatment before he arrived at Yaroslavl’s IK-1, a correctional facility an investigation into which has led to six officers being arrested and further 17 suspended, as well as a senior prison official saying he was “ashamed” of their conduct.

Vakhapov, a father of two, was a driver for a company in Yaroslavl when he was arrested after stopping to relieve himself on a roadside. He was charged with exposing himself to minors because there were children nearby.

He said he was railroaded into accepting a sentence of seven years in prison, during which he was beaten in another prison in the city of Rybinsk and had complained publicly to the Russian prosecutor through a lawyer for Public Verdict, Irina Biryukova.

After that, he said, guards at IK-1 were afraid to treat him harshly. Biryukova has since fled Russia after receiving death threats connected to the Makarov case.

Ruslan Vakhapov had complained to the Russian prosecutor through lawyer Irina Biryukova (pictured). Photograph: AP

Vakhapov said the system of using violence, both to maintain order and punish prisoners for perceived indiscretions, was widespread at IK-1 and other prisons, with certain prisons striving to earn a reputation as a place where inmates can expect harsh treatment.

They want inmates to know that this was a place where prisoners are beaten, he said.

As a rule, Vakhapov said, guards were afraid of leaving obvious signs of violence on prisoners’ faces. But they would carry out beatings often using batons, he said, against prisoners’ bodies, their necks, the ribs, their buttocks, and near the kidneys.

“If you pick up the Gulag Archipelago, and look at the whole system over the past 100 years, you can see that a lot of it is the same. Some things have been forgotten, but others have been remembered,” he said, referring to Alexander Solzhenitsyn’s study of the Soviet prison camp system. “They could beat you for anything. And each one of their shifts pretty much ended with at least one inmate being punished.”

Vakhapov has said he was urged to plead guilty by investigators and also told by a lawyer to prepare a bribe of 200,000 rubles (more than £2,300) to receive a suspended sentence. He refused and his mother later complained to an Investigative Committee of Russia hotline about the alleged request for a bribe.

The authorities quietly closed the case and transferred the investigator, but then reopened it months later. Vakhapov was found guilty and sentenced first to seven years in prison, despite counter-claims that evidence in the case was falsified. His prison term was eventually reduced to five and a half years. He maintains his innocence and his family has said they believe he was punished for speaking out.

Vakhapov did not see Makarov being beaten, and his screams were muffled by loud music that guards turned on to cover the beating, he told Public Verdict. But that night, Makarov had screamed through the doorway that he had been beaten so badly that he was passing blood when he went to the bathroom, Vakhapov added.

Now free, Vakhapov said he dreamed of taking revenge against the authorities through legal means, particularly against the powerful Investigative Committee he blames for his prosecution. The methods of police investigators have included several reports of the use of electric shocks and other extreme methods against Russian leftist activists to win confessions.

“If I could dream, I would find two dozen cases of false testimony carried out by the Russian Investigative Committee,” he said. “They ruined my life. As a man I have a desire to take revenge in a legal way.

“I didn’t have the opportunity to do much in my own case. But perhaps I can help in others.”

The roots of violence in prisons in Russia were myriad, he added: a culture of impunity, undereducated guards, prison wardens ready to look the other way or actively encouraging beatings.

Vakhapov expects little reform, despite the public backlash from the scandal in Russia’s bloated prisons bureaucracy. The country has one of the highest incarceration rates in the world, though it is still lower than in the US. On long trips to Russia’s remote prisons in the far north or elsewhere in the country, prisoners will sometimes face beatings with the knowledge that their bruises will fade by the time they arrive.

“Nothing will change,” Vakapov said. “They don’t know how to work differently. They need to fire 98% of the people from the head of the colonies down to the bottom.”

There is also pressure on inmates not to speak up about violence.

“It’s an enormous decision for an inmate” to complain, he said. “You better understand that you can lose everything.” Those who suffer seriously may be able to quietly negotiate future leniency, he said.

The trial brought out strong emotions in him, he said. On the one hand, “I was happy that the guards’ impunity would come to an end.”

But the next day, he said, he saw their wives and mothers queuing at the jail where they were being held, and recalled his own wife being bullied there while he was imprisoned.

“I felt bad for those wives and mothers at that moment,” Vakhapov said. “But of course the people in that video should pay the price for what they did.”