House Democrats have subpoenaed two associates of President Donald Trump’s personal lawyer, Rudy Giuliani, as part of their impeachment inquiry. The subpoenas came hours after the two men were arrested for campaign finance violations.

Three House committees subpoenaed Lev Parnas and Igor Fruman for documents they have so far refused to provide. The panels have also subpoenaed Giuliani.

Parnas and Fruman were involved in Giuliani’s efforts to urge Ukrainian officials to investigate Trump’s political rival Joe Biden and his family. That effort was also discussed by Trump in a July call with Ukraine’s president and is at the heart of the impeachment probe.

The men were arrested on a four-count indictment, including charges of conspiracy, making false statements to the Federal Election Commission and falsification of records.