Editor’s note: This story was originally published in The International Consortium of Investigative Journalists.

Michael Welu worked at the IRS for decades as a specialist in helping agents identify and investigate possible tax crimes. In an agency known for offices working in their own silos, Welu had the rare ability to move between divisions, dissecting and learning each office’s particular customs and procedures. But that experience had its own consequence for Welu: Seeing disparities in how the separate divisions treated different tiers of taxpayers left him exasperated and helped drive him into early retirement.

For more than 30 years, Welu watched the agency struggle with budget cuts and dwindling staff. What troubled Welu, he says, went deeper than just resource constraints.