Security Logs of Hillary Clinton’s Email Server Are Said to Show No Evidence of Hacking

WASHINGTON — A former aide to Hillary Clinton has turned over to the F.B.I. computer security logs from Mrs. Clinton’s private server, records that showed no evidence of foreign hacking, according to people close to a federal investigation into Mrs. Clinton’s emails.

The security logs bolster Mrs. Clinton’s assertion that her use of a personal email account to conduct State Department business while she was the secretary of state did not put American secrets into the hands of hackers or foreign governments.

The former aide, Bryan Pagliano, began cooperating with federal agents last fall, according to interviews with a federal law enforcement official and others close to the case. Mr. Pagliano described how he set up the server in Mrs. Clinton’s home in Chappaqua, N.Y., and according to two of the people, he provided agents the security logs. The law enforcement official described the interview as routine. Most of those close to the case spoke on condition of anonymity because they were not authorized to discuss the continuing investigation.

Mrs. Clinton’s work-related emails as secretary of state, which have been made public as part of a Freedom of Information Act lawsuit, show that she received spam emails intended to try to lure her into clicking a malicious link. Those emails, known as “spear phishing” attempts, were traced to Russia, but it was not clear from the emails alone whether anyone clicked on those links or whether the security was compromised.

Mr. Pagliano told the agents that nothing in his security logs suggested that any intrusion occurred. Security logs keep track of, among other things, who accessed the network and when. They are not definitive, and forensic experts can sometimes spot sophisticated hacking that is not apparent in the logs, but computer security experts view logs as key documents when detecting hackers.

Mrs. Clinton’s campaign reiterated Mr. Pagliano’s information on Thursday. “We’re not aware of any evidence whatsoever that the server was hacked,” said Brian Fallon, a campaign spokesman.

Mrs. Clinton’s exclusive use of a private email server prompted an F.B.I. investigation into whether she or her aides mishandled classified information. Of 30,068 emails released by the State Department, 22 have now been classified by the State Department as “top secret,” 65 are classified as “secret,” and 2,028 have received the lowest classification level of “confidential.”

The question of whether Mrs. Clinton’s server was hacked is separate from whether a crime occurred. But if the information was never compromised, it provides a basis for her supporters to portray Mrs. Clinton’s use of a private account as a mistake, but ultimately an inconsequential one.

Barring any changes, the F.B.I. investigation could end by early May. Then the Justice Department will decide whether to file criminal charges and if so, against whom.

Federal law makes it a crime to knowingly remove classified information from secure government channels or to allow classified information to be removed through “gross negligence.”

Many of the “secret” and “top secret” emails were written or forwarded by Mrs. Clinton’s senior aides. None of the emails were marked classified at the time.

Mr. Pagliano, who last year invoked his Fifth Amendment right not to testify before Congress, cooperated with the F.B.I. under a limited immunity deal. Limited immunity, which means that prosecutors may not use Mr. Pagliano’s words against him, is a far more narrow agreement than what is commonly known as “blanket immunity,” in which the government promises not to prosecute someone for crimes.

Mark MacDougall, Mr. Pagliano’s lawyer, said in an email that the limited immunity deal allowed his client to answer specific questions from investigators freely. “That’s all there is to it,” Mr. MacDougall said in an email. “Every citizen has that right. The government has the authority to grant immunity in order to obtain answers. In this case, they exercised that authority, we reached an agreement, and Bryan answered the questions.”

It is common for lawyers to request — and receive — such deals before allowing their clients to cooperate. Independent lawyers say that is true even in cases in which witnesses have nothing to hide.

“Any good lawyer is going to say ‘I want immunity before I talk,’” said Barbara Van Gelder, a Washington lawyer with the firm Cozen O’Connor, who has represented numerous witnesses in high-profile congressional and Justice Department investigations. “Just because someone gets immunity isn’t indicative of guilt. It’s just protection.”

Mrs. Clinton is the front-runner in the race for the Democratic presidential nomination. While aides see a clear path to the convention in July, the fallout from her emails is likely to create distractions in the weeks ahead. F.B.I. agents could seek to question her closest aides, and possibly Mrs. Clinton herself before they close their case. Mrs. Clinton has offered to meet with investigators and has encouraged her aides to cooperate.