The second largest (on paper, at the time) biodiesel credit producer in the US was completely fraudulent:

https://www.reuters.com/article/epa-biofuels-lawsuit/trading...

And he wasn't caught because the EPA did their jobs (they didn't). He got caught because he bought a ton of sports cars and his neighbors assumed he was a drug dealer or something similar and got local PD to start investigating.

Edit: there was an episode of American Greed about it too - https://m.imdb.com/title/tt6806100/plotsummary/?ref_=tt_ov_p...