I happen (by chance) to be friends with both Marshall Ulrich and the US District Attorney that prosecuted Engle. I was telling Marshall one night at dinner the story of how, when after seeing and hearing himself on a video they played at the trial, Engle says "Wow, I guess I do come off as kind of a jackass". Of course, Marshall isn't the biggest fan of Charlie so he got quite a good laugh out of this story.
Engle was a small fish that happened to have some fame and notoriety behind him due to the running exploits. The IRS agent probably said to himself, "How does he afford to do this?" Who can just take off work for months and months at a time to run. Who can afford 2 mortgages without a full time job?
I'm not saying that they shouldn't go after the loan officer that forged income levels or the one that approved it or many others in the process. They should, but Engle has never admitted any fault at all, either. He is a recovering drug addict because he finally owned up to and accepted responsibility for his drug problem, rather than blaming others. It's a shame he can't do the same in this aspect of this life.