The inspector general, Michael E. Horowitz, has been asking witnesses why FBI leadership seemed unwilling to move forward on the examination of emails found on the laptop of former congressman Anthony Weiner (D-N.Y.) until late October — about three weeks after first being alerted to the issue, according to these people, who spoke on the condition of anonymity to discuss the sensitive matter.
A key question of the internal investigation is whether McCabe or anyone else at the FBI wanted to avoid taking action on the laptop findings until after the Nov. 8 election, these people said. It is unclear whether the inspector general has reached any conclusions on that point.
A major line of inquiry for the inspector general has been trying to determine who at the FBI and the Justice Department knew about the Clinton emails on the Weiner laptop, and when they learned about them. McCabe is a central figure in those inquiries, these people said.
The FBI declined to comment, as did a spokesman for the inspector general. An attorney for McCabe did not respond to a request for comment.
On Monday, McCabe left the FBI, following a meeting with FBI Director Christopher A. Wray in which they discussed the inspector general's investigation, according to people familiar with the matter. Horowitz announced in January 2017 that he was examining the Justice Department's handling of the Clinton investigation. His report is expected in the spring.
The matter of the Weiner laptop emails has been debated publicly for more than a year, in part because many Clinton supporters say the FBI tilted the 2016 race toward Donald Trump when it announced in late October that it was reopening its probe into Clinton's use of a private email server when she served as secretary of state.
Key parts of what went into that decision have remained murky and are a major focus of the inspector general's probe, according to people familiar with the matter.
In late September 2016, FBI agents in New York were investigating Weiner for possible Internet crimes involving a teenage girl. In the course of that probe, they discovered that his laptop contained thousands of work emails belonging to Weiner's then-wife, Huma Abedin. Abedin was a longtime aide to Clinton, and agents wanted to know whether the emails in question might shed new light on the Clinton investigation, which had been closed in July without any charges.
The New York FBI office alerted FBI headquarters to the new email issue within days — accounts differ as to when precisely, but McCabe was aware of the matter by late September or early October at the latest, according to the people familiar with the matter. The agents on the Weiner case wanted to talk to the Clinton email investigators and see whether the messages were potentially important. Some people familiar with the matter said officials at FBI headquarters asked the New York agents to analyze the emails' metadata — the sender, recipient and times of the messages — to see whether they seemed relevant to the closed probe.
McCabe was involved in those discussions, but there are differing accounts about how much then-FBI Director James B. Comey understood about the matter in the early days of October.
An attorney for Comey could not immediately be reached for comment.
Some people involved at the time said Comey learned of the issue around the same time as McCabe. Others contend Comey did not know about it until weeks later. Senior Justice Department officials, according to several people familiar with the issue, were not notified until mid-October.
But for a period of at least three weeks, according to people involved at the time, nothing much happened — a lag that has sparked the inspector general's questions.
McCabe's defenders in law enforcement say that there was nothing nefarious going on — officials were pursuing a careful process of determining whether the emails might be relevant, and that took time.
Other law enforcement officials, however, have said they are concerned that the issue seemed to die for a period of time at McCabe's desk, without explanation.
On Oct. 24, 2016, the Wall Street Journal reported that McCabe's wife had received hundreds of thousands of dollars in campaign contributions from a close ally of Clinton, then-Virginia Gov. Terry McAuliffe. The donations were for McCabe's wife's unsuccessful run as a Democrat for the Virginia state legislature.
The dormant laptop issue then appeared to gain new attention inside the FBI and Justice Department. At a meeting of senior officials of both agencies, senior Justice Department official George Toscas asked about the status of the inquiry into the emails on Weiner's laptop, according to people familiar with the matter.
At the same time, the FBI was facing a new set of questions, this time about McCabe's role in a stalled probe into the Clinton Foundation. Some within the FBI felt McCabe had repeatedly moved to hamstring that probe and were suspicious of his motives for doing so, according to people familiar with the matter.
McCabe's defenders inside federal law enforcement have repeatedly said he tried to navigate a sensitive political investigation between Justice Department officials who thought the probe was going nowhere and FBI agents who believed they were being blocked from issuing subpoenas and taking other steps that could uncover critical evidence.
In the midst of fielding questions on that subject, Comey decided on Oct. 28 to notify Congress by letter that he was reopening the Clinton email investigation to see whether the Weiner laptop provided new evidence. In that letter, Comey said he received a formal briefing on the laptop issue a day earlier. The following week, Comey sent a second letter saying that the emails in question did not change the FBI's conclusions about the Clinton case. At that time, officials said the reason Comey did not notify Congress in early October, when the FBI first learned of the issue, was that the bureau wanted additional information before proceeding.