His hair is unkempt and his face unshaven. Dark bags encircle his eyes. He is exhausted and his muscles ache. He has endured stomach and digestive problems for more than a month and, as a result, he looks malnourished. Because he has lost weight, he repeatedly pushes his oversized square-framed glasses up the bridge of his nose, which use to stay put against his round face.
Despite his emaciated condition, Potekhin is in good spirits like any man who just got a new lease on life. Last week, Moscow-backed rebels released him, having held him captive for nearly two months.
On Aug. 7, the 38-year-old civic activist was visiting Donetsk when Kalashnikov-wielding militants in this eastern Ukrainian metropolis -- now a separatists stronghold -- held him up after he took a photograph of the Liverpool hotel, where he had once stayed with a girlfriend. Unbeknownst to him, the hotel was now a base for the rebels who saw him taking pictures and became suspicious.
When they inspected his passport and discovered he lives in Kiev, Ukraine's capital, they accused him of being a spy for government forces -- their sworn enemy in the six-month conflict that has ravaged eastern parts of the country. In short order, they threw a bag over his head and jailed him inside a power plant turned modern art center turned dungeon and munitions storage facility, which they referred to as Izolyatsia which means 'isolation.'
"First thing they tell everyone when they bring them in: 'We will execute you," Potekhin told me the morning after his release.
For 48 days, the activist was subjected to various forms of humiliation and hard labor as well as intimidation bordering on torture. Separatist are suspected of holding hundreds of other civilians in extrajudicial detention.
Potekhin was held in a tiny, dank cell which he shared with as many as 30 people, though the number of prisoners in the cell fluctuated.
"I know some jails which were turned into art spaces, but this is the only art space I know that was turned into a jail," he said. "Even in a bad jail you have a toilet and water in the cell. There is nothing like that here. Merely a bucket shared among all."
His fellow captives -- "hundreds" in all, he says -- included drug addicts and drunks picked up off the street for public indecency as well as local businessmen from whom the rebels extorted money to fund their campaign. Rather than ransoms, he says, the rebels called the forced payments "donations."
He and his fellow captives slept atop pieces of polystyrene and huddled together to stay warm during the chilly nights. Their captors fed them only twice a day - meals that typically consisted of cold, tasteless porridge and soups.
"It was impossible to eat that food. It's just shit," Potekhin says. "Sometimes we had soup. From day to day you could get hot, fresh soup. But then you could get the same soup the next day and a third day."
Those who were "not dangerous [but] behaved," were let outside on occasion to do manual labor.
"First it was quite hard work: Moving several tons of ammunition, arms every morning," he explains. "But this was the only chance we could breath fresh air."
Often they were ordered to dig trenches or clean streets. At one point, he and some others were taken to a local Toyota dealership that had been shuttered because of the violence in Donetsk. There, the rebels ordered them to push new trucks and cars from the lot to be either appropriated or sold.
As he speaks of the incident, a man limps into the Ramada restaurant with a group of armed rebels in camouflage fatigues. Pointing to the man, Potekhin says: "You see him? He was the one who took us to steal cars."
Now slouched in his seat and out of the line of sight of his captor, Potekhin discusses the interrogations he endured inside the renovated art center, painting a surreal scene.
"There were paintings on the wall, installations, children's artwork and painted, colorful walls all around," he says, adding that he was only lightly beaten by the rebels.
"They hit me in the back," he says, adding that they did, however, fire their automatic rifles near his head during the interrogations "not to kill me but to frighten me."
Potekhin estimated some 150 soldiers were based at Izolyatsia, and it was them - not the prison staff - who lashed out violently at the prisoners.
"Most of those beaten were not beaten by prison staff, but they were beaten by the fighters," who used those opportunities to take out their frustrations, he says.
"Every time they were beating, they were saying Ukrainians from Kiev and western Ukraine 'rape women and kill children.'"
Potekhin, who rose to prominence during Ukraine's 2004 Orange Revolution, has worked for more transparent presidential elections. His father served as diplomat in the Ukrainian embassy in Washington, and in the past years, Potekhin himself has worked closely with Western non-governmental organizations, such as the U.S.-Ukraine Foundation, for which he headed a project on voter education.
He is an advocate for non-violent resistance, and during the Euromaidan Revolution that toppled former President Viktor Yanukovych, he urged anti-government protesters in Kiev not to brandish weapons and trained other activists in passive resistance.
Over the course of the conflict, both sides have been blamed for firing rockets into cities here. More than 3,000 people, including civilians, fighters and passengers aboard Malaysia Airlines Flight 17, have been killed since the onslaught of the conflict in mid-April, according to the United Nations. Hundreds of them died when shells crashed into their homes.
With plans to pen a story for Canada's Peace Magazine, he came to Donetsk last month to check out reports that Ukrainian forces have been shelling residential areas.
Instead - to his own and others' surprise - he found himself accused of being a combatant.
He describes the Donetsk People's Republic, the name given by the separatists to this eastern region, as "a police state."
"It's like 1917 and 1937," he says, the former being the year of the Russian Revolution, the latter the year of the Great Purge - a campaign of political repression in the former Soviet Union orchestrated by the dictator Joseph Stalin.
"One of the cells where I was kept was next to the entrance to the place where all the [new] prisoners were taken and beaten," he explains. "Almost every night, we could hear people beaten next to our cell. Later we would see them all bloody."
Over the course of his time in captivity, he attempted to engage in conversations with the rebels, appealing to them to release him and other captives, trying to talk some sense into them.
"When I was arrested, I said 'Look, guys, I'm against violence, I'm against this war, and I'm for your independence. And here is a chance,'" he says. But they weren't interested."
The rebels did offer him a chance to be released early, if he would work as a correspondent for Russia's Life News, a controversial agency that has itself in the past interrogated prisoners who were seen in terrible conditions. The private television channel is said to have close ties to Russian security services.
Potekhin refused the deal.
"It is impossible to have a nice state here or to have stable peace with Ukraine, because they are fighters," he explains. "The only thing they know is how to fight."
Asked why the rebels decided to release him, Potekhin says, it might have been prompted by the hunger strike he announced a week earlier.
"They were very agitated by this," he explains. "But they just said they made a mistake."
Christopher Miller, Mashable