If you haven't read it already, I strongly recommend the Knapp Commission Report. Its about police corruption in New York City in 1972, but its lessons on systemic and institutionalized corruption are highly transferable to other contexts.

Probably the most common naive mistake I see is people thinking their subfield is special and they are the first to really notice / understand fraud within it. I've certainly seen people in the "sleuth community" (scientific fraud whistle blowers) reinvent the wheel a few times.

All fraud is basically the same. Financial, scientific, police corruption...it almost doesn't matter. I'm not even the first to say this. A really good summary can be found in Ashforth 2003 ("The Normalization of Corruption in Organizations").

So, with the caveat that I haven't read your work yet and maybe you already know, I'd say look at past corruption far outside your area of interest / expertise. There's a lot you can learn there. Police corruption reports are usually great because of how accessible they are in several senses (more numerous, usually simple to understand), but I have no police related agenda to push here and it really doesn't matter where you decide to look. Just pick any Commission and read their findings.

In the opening words of the Knapp Commission "We found corruption to be widespread".