Update, 6:45 p.m.: Here's a wrapup of what we know and don't know about Friday's developments at this time.
Update, 3:30 p.m.: What did we ever do to deserve this horrible world that we live in? From the New York Times:
American law enforcement officials said Friday that the new emails uncovered in the closed investigation into Hillary Clinton’s use of a private email server were discovered after the F.B.I. seized electronic devices belonging to Huma Abedin and her husband, Anthony Weiner.
Weiner is being investigated by U.S. attorney Preet Bharara for having possibly sent sexually explicit text messages to a minor. He and Abedin, Clinton's campaign co-chair, are separated.
Update, 3:10 p.m.: OK, there's a little more clarity developing here. Here's NBC's Pete Williams (who's been covering the Justice Department for decades and is presumably well-sourced) reporting that senior officials "familiar with the thinking behind [Comey's] letter" say the newly discovered emails in question 1) were not sent by Hillary Clinton, 2) do not appear to have intentionally been withheld from the FBI, 3) were not discovered via the investigation into the John Podesta or Democratic National Committee hacks. Williams adds (in a cautious, hedged manner) that the new development does not appear to be a "game changer."
NBC’s Pete Williams: Sr. officials say—During separate investigation “a device” led to add'l emails–not from Clinton https://t.co/QmmNoxXhOx— Bradd Jaffy (@BraddJaffy) October 28, 2016
Then there's this, from the AP.
BREAKING: US official: Newly discovered emails related to Clinton investigation did not come from her private server.— The Associated Press (@AP) October 28, 2016
So—an email relevant to the investigation, but one that wasn't sent by Clinton and wasn't on her server, was discovered in the course of ... something.
Original post, 1:27 p.m.: Well, here's a twist: FBI director James Comey just wrote a letter to a number of congressional committee chairs revealing that the agency has for some reason found more emails related to the Hillary Clinton private-server case and is investigating them to determine whether they contained classified information.
The text of the letter:
In previous Congressional testimony, I referred to the fact that the Federal Bureau of Investigation (FBI) had completed its investigation of former Secretary Clinton's personal email server. Due to recent developments, I am writing to supplement my previous testimony.
In connection with an unrelated case, the FBI has learned of the existence of emails that appear to be pertinent to the investigation. I am writing to inform you that the investigative team briefed me on this yesterday, and I agreed that the FBI should take appropriate investigative steps designed to allow investigators to review these emails to determine whether they contain classified information, as well as to assess their importance to our investigation.
Although the FBI cannot yet assess whether this material may be significant, and I cannot predict how long it will take us to complete this additional work, I believe it is important to update your Committees about our efforts in light of my previous testimony.
Your guess is as good as mine as to what other case Comey is referring to or why the FBI didn't already have all of Clinton's available emails after its yearlong investigation. I'll update this post when/if more information becomes available.