Serhiy Bolvinov, the chief police investigator for Kharkiv region said this in a recent interview.
A mass grave of more than 440 bodies has been found in the eastern city of Izium, Ukraine.
The bodies were found after Ukrainian forces recently recaptured the region from Russian forces.
The revelation was made by a regional police official on Thursday September 15, adding that some of the people had been killed by shelling and air strikes.
Serhiy Bolvinov, the chief police investigator for Kharkiv region, told Sky News that forensic investigations would be carried out on every body.
"I can say it is one of the largest burial sites in a big town in liberated (areas)... 440 bodies were buried in one place," Bolvinov said.
"Some died because of artillery fire ... some died because of air strikes," he said.
The discovery comes after thousands of Russian troops fled Izium last weekend following a massive counter offensive by Ukranian forces. Since the beginning of the month Ukraine has reclaimed 8000 km of land from Russian forces, according to president Volodimir Zelensky.
Reacting to the discovery of mass Graves, Zelensky put the blame on Russia and likened the discovery to what happened in Bucha, on the outskirts of the capital Kyiv in the early stages of the late February invasion by Russian forces.
Ukraine and its Western allies have accused the Russian forces of perpetrating war crimes there. Russia has repeatedly denied it targets civilians or has committed war crimes.
"Russia is leaving death behind it everywhere and must be held responsible," Zelensky said in a video address on Thursday night, September 15.