Researchers found nearly two dozen detention, interrogation, and processing centers in

• Researchers have found a network of detention, interrogation, and processing centers in occupied Ukraine.
• A new report documents at least 21 facilities used by Russian forces and Russian-backed proxies.
• Ukrainians have described harrowing experiences in Russian “filtration systems” during the war.

A sprawling network of nearly two dozen detention, interrogation, and processing centers, as well as what appears to be mass graves, were found in Russian-occupied Ukraine, researchers said on Thursday.  

Researchers from Yale University’s Humanitarian Research Lab, with the support of the State Department, published a report on Thursday documenting at least 21 facilities that appear to be part of a so-called “filtration system” in the Donetsk People’s Republic, territory in eastern Ukraine run by Kremlin-backed pro-Russian separatists. 

The filtration system appears to contain a network of registration, holding, interrogation, and detention facilities that Russian forces and Russian-backed proxies operate for Ukrainian civilians and prisoners of war, the report said. 

Researchers also said they found disturbed earth that is “consistent” with mass graves at a correctional facility. 

There is evidence that the system was created before Russian forces invaded Ukraine on February 24, researchers said, and it “likely grew” after Russian President Vladimir Putin’s forces captured the southern port city of Mariupol in April. 

Researchers said the report was prepared using a process of open source analysis and documentation, and each alleged filtration cite had to be corroborated using multiple independent sources. 

The research is a product of the Conflict Observatory Program, which the State Department announced in mid-May to “capture, analyze, and make widely available evidence of Russia-perpetrated war crimes and other atrocities in Ukraine.” 

Throughout the six-month-long war, Ukrainians have described harrowing experiences in Russia’s so-called “filtration system.” Civilians have said they were fingerprinted and told to hand over their phones to Russian forces, subjected to hours of interrogation, and forced to strip and sleep on the floor.  

Ukrainian officials have also accused Russia of deporting citizens from captured cities in eastern Ukraine to remote areas deep within Russia, comparing the tactic to something that Nazi Germany did during World War II. 

“President Putin and his government will not be able to engage in these persistent abuses with impunity,” the State Department said on Thursday after the report was published. “The people of Ukraine deserve justice, and the United States will continue to stand united with them for as long as it takes.”