Russia will be held accountable for war crimes and violations of international law allegedly committed by its forces in Ukraine, a European Union official vowed, amid mounting Ukrainian and international efforts to gather evidence for future criminal investigations.

In an interview with RFE/RL at its headquarters in Prague, Eamon Gilmore, the EU special representative for human rights, also suggested that Russian President Vladimir Putin might be put on trial one day, not unlike what happened with Serbian President Slobodan Milosevic after the bloody and violent breakup of Yugoslavia.

“Milosevic never thought he would face a court or face a tribunal in The Hague when he was committing war crimes,” Gilmore said in the interview, conducted on May 10.

“People who are responsible can be held to account no matter how long it takes,” he said.

Ukrainian and international investigators have been rushing to interview witnesses, documents alleged crimes, and gather evidence of alleged Russian crimes for use in any future criminal proceedings.

In the wake of the withdrawal of Russian troops from districts north of Kyiv last month, officials have been looking at whether civilians were summarily killed or executed, as well as a growing body of evidence pointing to possible rape and sexual violence.