Former Ukrainian Prosecutor General Yuri Lutsenko told the Washington Post on Thursday that he does not believe Joe Biden's son, Hunter, has violated any Ukrainian laws.

Why it matters: A whistleblower complaint released Thursday details how beginning in March 2019, Lutsenko floated allegations that Joe Biden pressured Ukraine to fire former Prosecutor General Viktor Shokin in order to quash an investigation into a company called Burisma Holdings, where Hunter Biden served as a board member. Rudy Giuliani and President Trump capitalized on the allegations — which Lutsenko later walked back — in a campaign to get the Ukrainian government to open an investigation into Biden.

The big picture: Lutsenko first said that there was no evidence of wrongdoing by Biden or his son in an interview with Bloomberg in May. Nonetheless, Trump and Giuliani have continued to push for an investigation, even after House Democrats announced they would launch an impeachment inquiry into Trump for allegedly soliciting foreign interference in the 2020 election.

The whistleblower complaint states that according to multiple U.S. officials, Ukrainian leadership was "led to believe" that a phone call or meeting between Trump and President Volodymyr Zelensky — which Ukraine desperately wanted — would depend on whether Zelensky showed a willingness to "play ball" on the Biden issues aired by Lutsenko and Giuliani.

Go deeper: Read the whistleblower complaint with summaries of each section