"She said staff time and manpower devoted to the case is diverting from programs that more urgently need attention, so the FBI decided to close its active investigation."
I'm surprised they don't have an (even unannounced) THX-1138 style limit on how much effort they spend on a single suspect. My wife had her purse stolen and about $10,000 extracted from various accounts a few years back, and the amount of effort they spent on the case is far less than a 20th of this one.