Inside the FBI’s 2016 Hillary Clinton email probe: Did it miss key leads and why it still matters?

SAN FRANCISCO, CALIFORNIA - MARCH 24: Hillary Clinton speaks onstage during the Common Sense Summit on Kids and Families 2025 on March 24, 2025 in San Francisco, California.

A newly unsealed document from the US Department of Justice is reigniting long-standing concerns over how the FBI handled its 2016 investigation into former Secretary of State Hillary Clinton’s use of a private email server.

The 35-page document, described as a classified addendum to the DOJ Inspector General’s 2018 report, was made public on July 21, 2025, by the Senate Judiciary Committee. The release follows persistent efforts by Republican lawmakers, especially Senator Chuck Grassley, to declassify what his office calls the “Clinton annex.”

According to the annex, the FBI under then-Director James Comey failed to conduct a full-digital forensic analysis, neglecting to examine a thumb drive said to contain highly sensitive US government data, including emails from President Barack Obama and material from the State Department.

Background: What was the Clinton email controversy?

Between 2009 and 2013, Clinton exclusively used a private server located in her New York home to conduct all official State Department correspondence, bypassing the government’s official state.gov system.

Investigations later revealed that this setup had transmitted classified material over unsecured channels. Out of around 30,000 emails Clinton voluntarily returned, 110 emails in 52 threads were found to contain classified information, including eight threads with Top Secret content, 36 with Secret classification and eight labelled Confidential.

An additional 2,000+ emails were retroactively marked classified. A 2019 State Department review found 38 individuals culpable in 91 cases, though it determined there was “no persuasive evidence of systemic, deliberate mishandling.”

Despite these findings, Comey declared in July 2016 that no charges were warranted. “Although there is evidence of potential violations of the statutes regarding the handling of classified information, our judgement is that no reasonable prosecutor would bring such a case,” he said at the time.

What the newly released ‘Clinton Annex’ reveals

The declassified annex outlines what it calls critical investigative failures. Chief among them is the FBI’s inexplicable decision not to examine a thumb drive that held classified communications, some reportedly involving President Obama.

A draft memo had recommended targeted searches of the device, but this never occurred.

“This document shows an extreme lack of effort and due diligence in the FBI’s investigation of former Secretary Clinton’s email usage and mishandling of highly classified information,” Sen. Chuck Grassley said in a public statement.

“Under Comey’s leadership, the FBI failed to perform fundamental investigative work and left key pieces of evidence on the cutting room floor,”said Grassley.

In addition to the unexamined thumb drive, the annex also references destroyed or inaccessible devices, which limited investigators’ ability to conduct a full digital review.

The FBI’s probe largely focused on Clinton’s voluntarily submitted 30,000 emails, omitting large swathes of related communications, some of which may have had national security implications.

Political bias or inconsistency?

Grassley argues that the disparity in investigative standards between Clinton’s email case and the later Trump-Russia inquiry is glaring.

“The Comey FBI’s negligent approach and perhaps intentional lack of effort in the Clinton investigation is a stark contrast to its full-throated investigation of the Trump-Russia collusion hoax, which was based on the uncorroborated and now discredited Steele dossier,” said Sen. Chuck Grassley.

“Comey’s decision-making process smacks of political infection,” he added.

The Clinton annex had remained classified since July 2018, just weeks after the DOJ's main report was released. It is only now being disclosed following congressional pressure led by Grassley.

DOJ, DNI add new layers to the debate

Attorney General Pam Bondi, who, along with FBI Director Kash Patel, helped declassify the annex, said its release reflects a commitment to transparency.

“Today, the Department of Justice honored Chairman Grassley’s request to release information relating to former-FBI Director James Comey’s failed investigation into Hillary Clinton’s mishandling of highly classified information during her tenure as Secretary of State,” said Bondi.

“I commend Chairman Grassley for his unwavering, years-long commitment to exposing the truth and holding those who seek to conceal it accountable,” she added.

The controversy has also deepened with new revelations from Director of National Intelligence Tulsi Gabbard, who released previously classified intelligence alleging that Obama-era officials manipulated data to build the Trump-Russia narrative.

Gabbard said the intelligence “laid the foundation for what later became the protracted Trump-Russia investigation.”

Comey’s leadership under the spotlight again

Comey’s role during the 2016 election has long sparked debate -- both for not recommending charges against Clinton and for reopening the case just days before the election, only to re-close it soon after.

Comey later wrote in his memoir A Higher Loyalty that he may have been subconsciously influenced by the widespread assumption that Clinton would win the presidency.

Though the 2018 OIG report said there was “no evidence of political bias” in the FBI’s actions, critics now argue that newly declassified details challenge the completeness of that conclusion.

“I warned years ago that the Clinton investigation failed to hit the mark, and I’m grateful the American people can finally see the facts for themselves,” said Sen. Chuck Grassley.

“After nearly a decade in the shadows, this information is now coming to light thanks to Attorney General Pam Bondi and FBI Director Kash Patel’s dedicated efforts to fulfill my congressional request,” he added.