Ukrainian President Volodymyr Zelenskyy said Friday that his chief of staff, Andrii Yermak, who has also been their country's top negotiator in peace talks with the U.S. and Russia, has resigned, amid a corruption investigation.

Yermak resigned after anti-corruption investigators searched his residence earlier in the day, according to the Associated Press. 

Two national agencies probing corruption in Ukraine said the searches targeted Yermak. However, a Yermak spokesman said the anti-graft agencies had not served Yermak a notice of suspicion, meaning he was not a suspect in an investigation. The spokesman also said Tkachuk has not been informed about to what the searches are related, the wire service also reports.