Strzok & Charles Kable sent letters.
The letters sent by the FBI to the State Department were dated Oct. 23, 2015, and Jan. 20, 2016, and marked "for official use only," Vice News reports.
They were written by Peter Strzok and Charles Kable IV, who head the FBI's counterespionage section. They were sent to Gregory Starr, the assistant secretary at the State Department's Bureau of Diplomatic Security.
They were written during the FBI's investigation into Clinton's private server use.
In the October letter, Kable wrote: "The potential compromise was identified when, as part of a Freedom of Information Act (FOIA) request, the U.S. Department of State (DoS) and the ICIG reviewed electronic mail (email) communications from the private email accounts previously used by a former Secretary of State during her tenure at DoS.
"An initial review of this material identified emails containing national security information later determined by the US Intelligence Community to be classified up to the Top Secret/Sensitive Compartmented Information Level," he wrote.
https://www.newsmax.com/Newsfront/inspector-general-fbi-fears-clinton/2016/08/09/id/742886/