WASHINGTON — The FBI on Friday took the unusual step of releasing to the public documents related to its yearlong investigation into Hillary Clinton’s use of a private email server while secretary of state. The documents include a summary of her July interview with FBI agents as well as a detailed chronology of steps that investigators took in deciding whether criminal charges were warranted.

Here are some of the highlights from the documents:

IT ALL STARTED WHEN …

Clinton told the FBI that she directed her aides in early 2009 to create a private email account and that, “as a matter of convenience,” it was moved onto an email system maintained by her husband’s staff.

She said she was aware a private email server was located in the basement of her Chappaqua, New York, home but had no knowledge of the “hardware, software and security protocols used to construct and operate the server.”

According to the FBI investigation, Clinton contacted Colin Powell in January 2009 to ask about his use of a BlackBerry when he was secretary of state.

He warned her that if she used a BlackBerry to “do business,” her emails could become official public records. “Be very careful. I got around it all by not saying much and not using systems that captured the data,” he advised Clinton, the FBI said.

She also said she didn’t recall receiving guidance from the State Department on email policies and that she didn’t explicitly request permission regarding a private email account or server — but said no one at the State Department expressed any concerns about it.


CLASSIFICATION CONFUSION

Clinton told the FBI that she didn’t pay attention to particular levels of classified information, though she said she treated all classified information the same.

She said she could not give an example of how classification of a document was determined, and told the FBI that she relied on career professionals to handle and mark classified information.

At one point in the interview, she was presented with a 2012 email that included a “c” marking before one of the paragraphs. Though the marking was meant to connote that the material was “confidential” — the lowest level of classification — Clinton said she wasn’t sure.

She speculated that perhaps the “c” referenced the paragraphs being “marked in alphabetical order,” according to the FBI interview.

Either way, Clinton said she regarded the content of the email as a “condolence call” and questioned the classification level.


‘NONPAPER’ FAX

Some of the FBI questioning concerned a 2011 email exchange in which Clinton requested that a document be emailed to her instead of sent by secure fax. The email with aide Jake Sullivan caused a political uproar earlier this year after being made public.

The exchange focused on a set of talking points that Clinton wanted sent to her. After Sullivan said he was having issues getting her the document through secure fax, Clinton suggested he turn it “into nonpaper w/no identifying heading and send nonsecure.”

Clinton told investigators that she understood “nonpaper” to mean a document with no identifying marks of any kind that cannot be attributed to the U.S. government. She said she thought the practice went back “200 years.”

Presented with the email by the FBI, Clinton said she intended for Sullivan to remove the State Department letterhead and provide unclassified talking points. She said she had no intention of removing classification markings, and that she couldn’t recall actually receiving a “nonpaper” or secure fax.


EMAIL RETENTION — AND DELETION

Clinton aide Cheryl Mills told the FBI that Clinton decided in December 2014 that she no longer needed access to any of her emails older than 60 days. Mills instructed an unidentified person to modify the email retention policy on Clinton’s clintonemail.com email address to reflect the change.

After Clinton’s use of a private email account was publicly revealed in media accounts the following March, a House subcommittee investigating the Benghazi attacks asked for related emails to be preserved and turned over.

Sometime between March 25 and 31 — weeks after the server was disclosed — the unidentified person realized that he did not make the email retention policy changes that had been requested by Mills months earlier. That realization prompted an “oh (expletive) moment,” the person later told the FBI.

The individual then deleted an archive Clinton emails and used a program known as BleachBit, open source software that lets users shred files, clear Internet history and wipe free space on a hard drive.


FOIA OBLIGATIONS

Clinton said she never deleted or asked anyone to delete any of the emails to avoid complying with requests from the State Department, the FBI or her obligations under the Freedom of Information Act, which makes government agencies subject to public records requests.

She said she never had any conversations about using the email server as a way to get around her legal obligations under FOIA or the Federal Records Act, which imposes requirements for retaining government documents.


FOREIGN INTRUSIONS

The FBI said it did not find conclusive evidence that Clinton’s email server had been compromised by foreign hackers. But investigators said their forensic analysis was limited by the FBI’s inability to recover all server equipment and by the lack of complete server log data.

FBI Director James Comey has also said foreign government hackers were so sophisticated — and the server would be such a high-value target — that it was unlikely they would leave evidence of a break-in.

Bryan Pagliano, the tech expert who set up the server and spoke to the FBI under immunity, told the FBI there were no successful security breaches, but said he was aware of many failed login attempts — which he described as “brute force attacks.” Investigators also found multiple instances of phishing emails sent to Clinton’s account.


OLD PHONES

The FBI says its investigation identified 13 mobile devices that were potentially used to send emails, but the FBI was unable to examine them after the law firm that represented Clinton said it could not locate them. The FBI also identified five iPads that could have been used for emails.

According to the FBI investigation, a former Clinton aide named Monica Hanley often purchased replacement BlackBerrys for Clinton.

The devices would then be set up and synced to the server. When Clinton’s BlackBerry device would malfunction, her aides would help her get a new one. And once she transitioned to a new phone, the whereabouts of her old one would “frequently become unknown,” the FBI’s notes indicate.

One Clinton aide recalled to the FBI destroying her old mobile devices by breaking them in half or hitting them with a hammer.