Kao had credibility issues. He was now a felon trying to avoid a lengthy prison sentence. And there were other challenges. Building a corruption case against elected officials requires extraordinary proof of a quid pro quo arrangement, in part because the Supreme Court has narrowed what counts as bribery.

Even so, by the end of 2024, the agents had enough evidence to pursue a sweeping bribery probe that could ensnare top lawmakers of both political parties. They asked their supervisors to approve a new investigation and contemplated using undercover operatives to gather more evidence. Although their effort was in its early stages, and it was unclear where it would lead, FBI agents asked Kao extensive questions about his dealings with Collins and her office.

Then Trump returned to the White House. Consumed by a campaign of vengeance, he stacked the Department of Justice with his personal lawyers and demanded a purge of anyone who had ever investigated him.

The specialized FBI and DOJ teams handling public corruption investigations, some of which were involved in Trump-related cases, were eviscerated. One of the agents who had taken Kao’s confession was pushed out as retribution for her role in investigating Trump’s attempt to overturn the 2020 election. Dozens of agents and prosecutors quit amid the department’s destruction, including the career attorney assigned to Kao’s case.