I read the book about it, and it was actually an IRS agent who found a super old forum post where the guy announced he had created the Silk Road using a usernam

I read the book about it, and it was actually an IRS agent who found a super old forum post where the guy announced he had created the Silk Road using a username that was easily linked to his real name. The IRS guy figured it out and nobody would act on it because they all figured the FBI would know better and they should wait for the FBI to do it right. ... but actually he nailed it.