DONETSK, Ukraine – On a bench in a courtyard shaded by large poplars, Tanya takes a long drag of her skinny cigarette and pauses as she holds the smoke in her lungs. Then, enunciating each word slowly with the exhale, she tells me: “They took him.” The morning of her husband’s disappearance in late May was like any other: he awoke at dawn and dressed in the police uniform she had pressed for him the night before. He wolfed down the breakfast of sausage and salad she had prepared, and then kissed her goodbye. It was the last time she saw him.

Tanya is convinced that pro-Russian insurgents abducted her husband who often spoke publicly of the pride he felt wearing the Ukrainian uniform. But, fearing reprisals against herself and her husband — if he is still alive — she asked that his first name and their last name not be published.

Pro-Russian militants carry an man with his eyes covered outside the regional state building they seized in the eastern Ukrainian city of Donetsk on May 5, 2014. Image: GENYA SAVILOV/AFP/Getty Images

The week of her husband's disappearance, the insurgents came to the Artemivsk police station where her husband worked and delivered an ultimatum: work with us — or else. The officers were given until the end of the day to decide. Most didn’t wait that long, pledging their allegiance right then and there. Tanya’s husband was a notable exception, and Tanya believes that this is why he disappeared.

In the course of this conflict, pro-Russian militants have kidnapped hundreds of activists, journalists, police and civilians, human rights observers estimate, though exact numbers are hard to come by. Some abductees have been released after a few hours, days or weeks in captivity. On Friday, observers from the Organization for Security and Co-operation in Europe were freed, having been held hostage for a month.

But many others — especially local Ukrainians — remain in captivity, hidden inside dark and dank basements, suffering in horrific conditions.

An unidentified freed OSCE observer arrives in Donetsk early on June 27, 2014. The four observers from the Organisation for Security and Cooperation in Europe, who were abducted on May 26 by pro-Russian rebels in eastern Ukraine, appeared tired and tense Image: Alexander KHUDOTEPLY/AFP/Getty Images

As pro-Russian insurgents tighten their grip on the eastern regions of Donetsk and Luhansk, a climate of fear has reared its ugly head, though few locals are willing to talk about the scourge of kidnappings outside the relative safety of their kitchens.

Human rights observers say that, in the months since insurgents seized territory here in April, they have used kidnappings to intimidate the local population. On June 24, the UN Assistant Secretary-General for Human Rights Ivan Simonovic warned that the situation in eastern Ukraine is “rapidly deteriorating.” The below Facebook post shows prominent Ukrainian theater director Pavlo Yurov and the art curator Denys Hryshchuk, who have been held in captivity in Sloviansk since late April.

Having been blindfolded, tied up and thrown inside a van or the trunk of a car, many abductees are beaten, tortured with electrical shock, starved and even used as slave labor to dig trenches and erect roadblocks, according to Kateryna Sergatskova, a 26-year-old Russian reporter for the popular Ukrainian news website Ukrainska Pravda, and a leader of the campaign to document the cases of the disappeared. In an interview with Mashable, Sergatskova said most people in eastern Ukraine are terrified of the pro-Russian insurgents and hesitant to talk about loved ones who have gone missing for fear of retaliation. As a result, it has been hard to compile an exact list of the disappeared. She has a list with about 100 names — gathered from media reports and dozens of interviews in eastern Ukraine — and the list grows by the day. One of the worst abductions she documented was the case of three disappeared men found floating in a river, their stomachs slashed open, near the city of Sloviansk, an insurgent stronghold about 70 miles north of Donetsk.

In some cases, hostages are being used by the insurgents as human shields to prevent the Ukrainian armed forces from storming the buildings they occupy, and as bargaining chips to negotiate prisoner exchanges, according to Sergatskova, who said insurgents are currently holding as many as 200 people hostage — including activists, journalists and political opponents — in a security services building in Sloviansk.

Another 100 people are held captive in a seized police building in Horlivka, some 50 miles southeast of Sloviansk, according to Sergatskova. The city has been a center of the violence in the region. Volodymyr Rybak, a city council member who tried to replace the separatists’ flag atop a city building with the blue and yellow Ukrainian flag, was reportedly abducted, tortured and killed by insurgents, who left his mutilated body at the bank of a nearby river.

Alexander Borodai, Prime Minister of the self proclaimed 'Donetsk People's Republic', center, surrounded by pro-Russian fighters, smokes after releasing members of the OSCE Special Monitoring Mission in the city of Donetsk, eastern Ukraine Saturday, June 28, 2014. Image: Dmitry Lovetsky/Associated Press

Many others are held hostage for ransom. Sergatskova’s case list includes cases of people being forced to hand over their life savings — as much as $200,0000 — to ensure the safe return of their loved ones. The money is then used to fund the insurgency, she said. “I spoke with a man whose family needed to raise $60,000 in a matter of three hours for him to be released,” Denis Krivosheev, deputy director of the Europe and Central Asia Program at Amnesty International, told Mashable by phone after a recent field trip to eastern Ukraine. Among the people he spoke to during his trip was a man who said he had tried to commit suicide while in captivity, unable to endure the torture. Eventually the man was released. There is little likelihood that his tormentors will be brought to justice. “There are no police on the streets, and even if there were, there is no trust in the police," Krivosheev said. "If you get in trouble [in eastern Ukraine], there is nobody there to help you.”