WASHINGTON: Hillary Clinton told the FBI she relied on her staff not to send emails containing classified information to the private email server she used as secretary of state.

The revelation came Friday as the FBI, in a rare step, published scores of pages summarizing interviews with Clinton and her top aides from the recently closed criminal investigation into her use of a private email server in the basement of her Chappaqua, New York, home.

The Democratic presidential nominee told the FBI she never sought or asked permission to use a private server or email address during her tenure as the nation's top diplomat from 2009 to 2013. A prior review by the State Department's internal watchdog concluded the practice violated several polices for the safekeeping and preservation of federal records.

The latest developments highlight competing liabilities for Clinton. Either she made a conscious effort to prevent a full public accounting of her tenure at State or she was nonchalant about decisions with national security consequences and risks. The first scenario plays into Republican arguments and voter concerns about her trustworthiness and transparency, while the second casts doubt on her pitch as a hyper-competent, detail-driven executive.

Clinton campaign spokesman Brian Fallon said Friday the campaign was pleased the FBI had released the documents.

"While her use of a single email account was clearly a mistake and she has taken responsibility for it, these materials make clear why the Justice Department believed there was no basis to move forward with this case," Fallon said.

GOP presidential nominee Donald Trump countered that Clinton's "answers to the FBI about her private email server defy belief."

"After reading these documents, I really don't understand how she was able to get away from prosecution," Trump said in a statement.

Clinton has repeatedly said her use of private email was allowed. But over a 3½-hour interview in July, she told investigators she "did not explicitly request permission to use a private server or email address," the FBI wrote. Clinton said no one at the State Department raised concerns during her tenure, and she said everyone with whom she exchanged emails knew she was using a private email address.

The documents also include technical details about how the private server was set up. It is the first disclosure of details provided by Bryan Pagliano, the technology staffer who set up and maintained Clinton's IT infrastructure. Pagliano secured an immunity agreement from the Justice Department after previously refusing to testify before Congress, invoking his constitutional right against self-incrimination.

Large portions of the FBI documents were censored. The FBI cited exemptions protecting national security and investigative techniques. Previous government reviews of the 55,000 pages of emails Clinton returned to the State Department found that about 110 contained classified information.

Clinton and her legal team deleted thousands more emails she claimed were personal and private. The FBI report details steps taken by Clinton's staff that appear intended to hamper the recovery of deleted data, including smashing her old Blackberry smartphones with a hammer and using special software to wipe the hard drive of a server she had used.

Friday's release of internal investigative documents by the FBI was a highly unusual step, but one that reflects extraordinary public interest in the investigation into Clinton's server.

The FBI focused on whether Clinton sent or received classified information using the private server, which was not authorized for such messages. Clinton told the FBI she relied on others with knowledge about handling classified files not to send her emails inappropriately.

Clinton said she was unfamiliar with the meaning of the letter "c'' next to a paragraph and speculated that it might be "referencing paragraphs marked in alphabetical order." That particular email had been marked as classified at the confidential level, the lowest level of classification. Clinton said she did not pay attention to the level of classification "and took all classified information seriously," according to the FBI.

After a yearlong investigation, the FBI recommended against prosecution in July, and the Justice Department then closed the case. FBI Director James Comey said that while Clinton and her aides had been "extremely careless" in dealing with sensitive materials, there was no evidence they intentionally mishandled classified information.

The FBI's review also found no direct evidence that Clinton's server was hacked but said her system would be a high-value target for foreign intelligence agencies and a sophisticated attacker would have been unlikely to leave behind evidence of a breach. Clinton told the FBI she was unaware of specific details about the security, software or hardware used on her server.

Clinton also told the FBI she never deleted emails, nor instructed anyone else to do so, to avoid their potential release under the Freedom of Information Act.

However, the FBI report says Clinton contacted her predecessor, former Secretary Colin Powell, in January 2009 to inquire about his use of a BlackBerry. Powell, who also used a private email account, warned Clinton that if it became "public" that she used a smartphone to "do business," her emails could become official government records subject to disclosure.

"Be very careful," Powell cautioned Clinton in an email. "I got around it all by not saying much and not using systems that captured the data."

Clinton said she later directed her aides to create a private email account and said it was "a matter of convenience" to use the home server shared with her husband, former President Bill Clinton.

She added that "everyone at State knew she had a private email address," though in separate interviews several on her team told agents they had no idea she was using a private account.

Highlights of FBI notes on Clinton email investigation 

The FBI 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.

Highlights from the documents released Friday:

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 that 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 confusion.

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.

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 official heading that cannot be attributed to the U.S. government. She said she thought the practice went back "200 years."

Presented with the email, she said she believed she was asking Sullivan to remove the State Department letterhead and provide unclassified talking points. But she said she had no intention of removing classification markings, and she said she couldn't recall actually receiving a "nonpaper" or secure fax in that instance.

E-mail 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 then 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 person realized that he did not make the email retention policy changes that had been requested months earlier.

In an email to the FBI in May, the person said he had an "oh (expletive) moment" and, in late March, deleted an archive of emails. The person said he 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.

Clinton told agents there were never so many suspicious emails to cause concerns.