The State Department has identified more than a dozen individuals involved in security incidents connected to former Secretary of State Hillary Clinton's use of a private email server.

A review of the mishandling of classified information found 23 "violations" and seven "infractions" by 15 individuals, according to Mary Elizabeth Taylor, the assistant secretary of state for legislative affairs. Some of them "were culpable in multiple security incidents."

Taylor sent a letter to Sen. Chuck Grassley, R-Iowa, who is leading the congressional oversight of the security review.

"In every instance in which the Department found an individual to be culpable of a valid security violation or three or more infractions, the Department forwarded the outcome to the Bureau of Diplomatic Security's Office of Personnel Security and Suitability (DS/PSS), to be placed in the individuals' official security file," Taylor wrote on June 5. "All valid security incidents are reviewed by DS and taken into account every time an individual's eligibility for access to classified information is considered. This referral occurred whether or not the individual was currently employed with the Department of State and such security files are kept indefinitely."

The individuals were not identified, nor was it revealed if they were still employed at the State Department, per agency policy. The inquiry is ongoing, and Taylor said the number of people found culpable could increase.

Taylor said the violations of infractions by individuals still employed by the State Department were referred to the Bureau of Human Resources. A "broad range" of disciplinary or administrative actions that could be taken include "counseling, reprimand, suspension, and/or separation," Taylor wrote.

The State Department review began after the FBI investigated Clinton's use of an unauthorized server, hosted in the basement of her home in Chappaqua, N.Y., during her time as secretary of state from 2009 to 2013. Former FBI Director James Comey publicly recommended in 2016 that no charges be brought against Clinton, who was then a candidate for president, but admonished Clinton and her colleagues for being "extremely careless" in handling classified information.

One of the main controversies stemming from Clinton's emails was how a technician managing the server deleted 33,000 emails. The FBI was only able to recover about 5,000 of the emails, which were released in tranches up until earlier this year as part of a Judicial Watch lawsuit. Clinton has said she "never received nor sent any material that was marked classified," but the FBI found 110 emails did contain classified information.

Clinton's security clearance was withdrawn in the fall of 2018 at her request, along with those belonging to her former aide Cheryl Mills and others.

Grassley has repeatedly asked for updates on the State Department's review since 2017. In her letter, Taylor acknowledged that the large number of emails under scrutiny required "a significant dedication of time and resources."

Taylor said the agency is "making every effort to complete its review and adjudication" by Sept. 1, 2019.