This details the FBI's ultrasophisticated work in tracking down down the ill gotten gains from those very very evil Russian Hackers.
It goes into detail in how they were on top of things from day one.
Evidently they have very super sophisticated software in which they can track when bitcoins are moved from one wallet to another.
They were able to use their incredible skills to monitor the hackers moving bitcoins from one wallet to another until the hackers moved all of the bitcoins to a wallet that the FBI just happened to have all the keys and passwords to. Then they immediately seized them.