Glenn Greenwald: What's the answer to this?

A commenter here on Friday noted what appears to be a rather glaring contradiction in the case against Bruce Ivins. In response to criticisms that the FBI's case contains no evidence placing Ivins in New Jersey, where the anthrax letters were sent, The Washington Post published an article -- headlined "New Details Show Anthrax Suspect Away On Key Day" -- which, based on leaks from "government sources briefed on the case," purported to describe evidence about Bruce Ivins' whereabouts on September 17 -- the day the FBI says the first batch of anthrax letters were mailed from a Princeton, New Jersey mailbox. The Post reported:

A partial log of Ivins's work hours shows that he worked late in the lab on the evening of Sunday, Sept. 16, signing out at 9:52 p.m. after two hours and 15 minutes. The next morning, the sources said, he showed up as usual but stayed only briefly before taking leave hours. Authorities assume that he drove to Princeton immediately after that, dropping the letters in a mailbox on a well-traveled street across from the university campus. Ivins would have had to have left quickly to return for an appointment in the early evening, about 4 or 5 p.m.