Updated at 10:25 p.m. ET

Before Washington, D.C., had fully processed the late-night firing of Deputy FBI Director Andrew McCabe, who was let go by Attorney General Jeff Sessions less than 48 hours before his planned retirement after more than two decades of service to the bureau, the saga took several new, head-spinning turns Saturday.

The man leading the Justice Department's investigation into Russian interference in the 2016 election has been keeping busy.

Special counsel Robert Mueller has been on the job for about nine months. But he has already charged 19 people with wrongdoing — and won guilty pleas from the president's former campaign vice chairman and his former national security adviser.

Scholars who focus on politically charged investigations that may lead into the White House have been taking note.

Updated at 5:28 p.m. ET

Rick Gates, the business partner of Donald Trump's former campaign chairman Paul Manafort, pleaded guilty on Friday to two charges and will begin cooperating with federal prosecutors investigating the Trump campaign and Russian interference in the 2016 presidential election.

Gates appeared in federal court on Friday afternoon. He told Judge Amy Berman Jackson he was making the plea of his own free will.

President Trump spent the weekend at his Mar-a-Lago resort tweeting about the Russia investigation after a federal grand jury on Friday indicted 13 Russians and three Russian companies in connection with what prosecutors describe as a covert Russian campaign to help Trump win the presidency.

Updated at 10:35 p.m. ET

The FBI says that someone called its tip line to report concerns about Nikolas Cruz, who has told police he killed 17 people in a Florida high school this week — but that the bureau failed to follow protocols to assess the threat.

The bureau says a person close to Cruz contacted the FBI's Public Access Line on Jan. 5 to report concerns about him. Those concerns included information about Cruz's gun ownership, a desire to kill people, erratic behavior and disturbing social media posts.

Updated at 7:05 p.m. ET

The House intelligence committee voted without opposition on Monday to declassify a secret Democratic rebuttal to the once-secret Republican memo about alleged surveillance abuses that was unveiled on Friday.

The Democrats' document now goes to the White House, where President Trump will decide whether it should become public.

Updated 2:30 p.m. ET

President Trump joined his Republican allies on Friday in piling on with attacks about "bias" in the FBI and the Justice Department as Washington, D.C., waited on tenterhooks for the release of a controversial secret spying memo.

Updated at 3:30 a.m. ET Thursday

The FBI clashed with the White House on Wednesday over the much discussed Republican memo that alleges the bureau abused its surveillance powers. The bureau said it has "grave concerns" about the "accuracy" of the document that the president supports making public.

Meanwhile, the ranking Democrat on the House intelligence committee, which voted to release the memo, says Republicans secretly made "material changes" to the document after the decision to make it public.

Updated at 9:45 p.m. ET

FBI deputy director Andrew McCabe is leaving the bureau after more than 20 years on the job, according to an individual familiar with the matter.

McCabe stepped down Monday from his post as the bureau's No. 2 official, and as expected he will take accumulated leave and remain on the payroll until March when he is eligible to retire with full benefits. The departure plan had been in the works for a while.

President Trump used Twitter Saturday to suggest that Andrew McCabe, the FBI's increasingly embattled deputy director, was holding onto his position in a race against time to claim full pension benefits.

Trump said McCabe was "racing the clock" in one tweet Saturday:

"FBI Deputy Director Andrew McCabe is racing the clock to retire with full benefits. 90 days to go?!!!"