Russian spies are using hackers to target computer systems at law enforcement agencies in Ukraine in a bid to identify and obtain evidence related to alleged Russian war crimes, Ukraine’s cyber defense chief told Reuters on Friday.

The hackers, working across Russia’s foreign, domestic and military intelligence agencies, have stepped up digital intrusion campaigns targeting the Ukrainian Prosecutor General’s office and departments documenting war crimes, said Yurii Shchyhol, head of the State Service of Special Communications and Information Protection of Ukraine (SSSCIP), which handles cyber defense in the embattled country.

“There’s been a change in direction, from a focus on energy facilities towards law enforcement institutions which had previously not been targeted that often,” Shchyhol said.

“This shift, towards the courts, prosecutors and law enforcement units, shows that hackers are gathering evidence about Russian war crimes in Ukraine” with a view to following Ukraine’s investigations, he added.

The espionage activity will be flagged in an upcoming SSSCIP report, due to be published on Monday.

The report, a copy of which was reviewed by Reuters, says hackers were also trying to gather intelligence on Russian nationals arrested in Ukraine, with a view to “help these individuals avoid prosecution and move them back to Russia”.

“The groups we’ve identified as being engaged in this activity are part of Russia’s GRU and FSB intelligence agencies,” Shchyhol said.

Russia’s Foreign Ministry and the Federal Security Service (FSB) did not immediately respond to written requests from Reuters for comment. Russia’s GRU military intelligence agency could not be reached for comment.