This is according to what two unnamed “sources who have been briefed on the matter” will tell Yahoo News in July 2016. FBI officials privately meet with senior Clinton campaign officials and express concern that hackers are using “spear phishing” techniques to access the campaign’s computers. They ask the campaign to turn over internal computer logs and the personal email addresses of top campaign staffers to help the FBI’s investigation. But the campaign declines to do so after deciding the request for personal data is too broad and intrusive. The FBI doesn’t give any mention as to who the hackers might be.
One month later, the campaign will learn on its own that its computers have been hacked and they will use a private cybersecurity company to combat the hackers.
Yahoo News will comment that the FBI’s “warning also could raise new questions about why the campaign and the DNC didn’t take the matter more seriously.”
At the time, the FBI has an active investigation into Clinton’s email usage while she was secretary of state, and Clinton’s campaign isn’t sure how extensive that inquiry is. There have been media reports that the investigation extended into unethical practices at the Clinton Foundation, which could theoretically include interest in more recent communications.
Yahoo News will report that, according to an unnamed internal source, “Campaign officials had reason to fear that any production of campaign computer logs and personal email accounts could be used to further such a probe.” But the FBI insists that its request for data to combat the hacking has no connection to any other investigation, and since there is no subpoena forcing the issue, the Clinton campaign turns down the request. (Yahoo News, 7/29/2016)