That's convenient

Federal investigators "formally concluded" the 2001 anthrax murder case against bioweapons scientist Bruce Ivins on Friday, releasing a 92-page prosecutor's summary and some 2,700 pages of documents related to the case.

Ivins committed suicide on July 29, 2008, following two years of FBI agents focusing on him as the lead suspect in the "Amerithrax" investigation. The 2001 anthrax mailings killed five people, sickened 17, and paralyzed the nation's postal system.

"As disclosed previously, the Amerithrax investigation found that the late Dr. Bruce Ivins acted alone in planning and executing these attacks," the Justice Department said in a statement as it released the files.

http://www.usatoday.com/news/washington/2010-02-19-anthrax-case-closed_N.htm

Translation: They don't know, so they're blaming the guy who committed suicide.