Welcome to Pay Dirt—exclusive reporting and research from The Daily Beast’s Lachlan Markay on corruption, campaign finance, and influence-peddling in the nation’s capital. For Beast Inside members only.

One of the most influential lobbying firms in Donald Trump’s Washington, D.C. cut a five-figure check late last year to a Ukrainian-born businessman who has assisted the president’s team in efforts to dig up dirt on leading Democratic presidential nominee Joe Biden.

The firm, Ballard Partners, wrote a check for $22,500 in September to Lev Parnas, an executive at the firm Global Energy Producers. Parnas and his partner at the company, Igor Fruman, have teamed up with Trump attorney Rudy Giuliani to solicit damaging information in Ukraine about Biden and his son Hunter. Giuliani confirmed that he’s worked with both men in an interview with PAY DIRT last week.