KYIV — The first batch of recordings was embarrassing. The second is devastating. In late April and early May, Ukrainian journalists and anti-corruption activists released a torrent of audio files — hundreds of hours of conversations involving Timur Mindich, the businessman already at the center of the country's energy corruption scandal, and a roster of names that reads like a directory of presidential power. There is Andriy Yermak, the president's chief of staff and widely regarded as the...

KYIV — They arrived without warning, as these things now do: audio files, compressed and anonymized, uploaded to a Telegram channel with a modest following and a reputation for publishing what Ukraine's mainstream outlets would not touch. The voices were clear enough. One belonged to Timur Mindich, the businessman at the center of the country's widening energy corruption scandal. The others belonged to senior officials — deputy ministers, parliamentary faction leaders, the kind of people...

KYIV — Timur Mindich does not hold a government post. He has never run for parliament, never chaired a regulatory commission, never appeared on an official org chart inside the Ministry of Energy. Yet when anti-corruption investigators raided his properties last month, they described the resulting case as one of the most significant since Russia's full-scale invasion began. The numbers attached to the alleged scheme — more than $100 million in inflated procurement contracts, offshore shell...