Hillary Clinton is flanked by Reps. Maxine Waters, left, and Karen Bass, both California Democrats, at the California African American Museum in Los Angeles on May 5. (Lucy Nicholson/Reuters)

Prosecutors and FBI agents investigating Hillary Clinton’s use of a personal email server have so far found scant evidence that the leading Democratic presidential candidate intended to break classification rules, though they are still probing the case aggressively with an eye on interviewing Clinton herself, according to U.S. officials familiar with the matter.

FBI agents on the case have been joined by federal prosecutors from the same office that successfully prosecuted 9/11 conspirator Zacarias Moussaoui — and who would handle any Edward Snowden case, should he ever return to the country, according to the U.S. officials familiar with the matter. And in recent weeks, prosecutors from the U.S. Attorney’s Office in the Eastern District of Virginia and their FBI counterparts have been interviewing top Clinton aides as they seek to bring the case to a close.

CNN reported Thursday that longtime Clinton aide Huma Abedin was among those interviewed. A lawyer for Abedin did not immediately return an email seeking comment.

The involvement of the U.S. Attorney’s Office is not indicative that charges are imminent or even likely. One official said prosecutors are wrestling with the question of whether Clinton intended to violate the rules, and so far, the evidence seemed to indicate she did not.

Dana Boente, U.S. attorney for the Eastern District of Virginia. (Justice Department)

But the investigation is not over, and if charges are brought, Clinton would face a team that is no stranger to high-profile cases involving classified material. Last year, for example, prosecutors in the district won a conviction of a former CIA officer who was involved in a highly secretive operation to give faulty nuclear plans to Iran and accused of leaking details of the effort to a reporter.

The officials spoke on the condition of anonymity because they were not authorized to discuss the ongoing probe. An FBI spokesman and a spokesman for the U.S. Attorney’s Office in the Eastern District of Virginia declined to comment.

Clinton campaign spokesman Brian Fallon said in a statement: “From the start, Hillary Clinton has offered to answer any questions that would help the Justice Department complete its review, and we hope and expect that anyone else who is asked would do the same. We are confident the review will conclude that nothing inappropriate took place.”

The Justice Department has granted immunity to at least one former State Department staffer, Bryan Pagliano, who worked on Clinton’s private email server. There is no indication a grand jury has been convened in the case.

U.S. officials also dismissed claims by a Romanian hacker now facing federal charges in Virginia that he was able to breach Clinton’s personal email server. The officials said investigators have found no evidence to support the assertion by Marcel Lehel Lazar to Fox News and others, and they believed if he had accessed Clinton’s emails, he would have released them — as he did when he got into accounts of other high-profile people.

D.C.-area lawyers commonly refer to the Eastern District of Virginia as the “rocket docket” for the speed with which cases move through it. The U.S. Attorney’s Office there has about 300 lawyers and other employees working in Alexandria, Richmond, Norfolk and Newport News and has long had a reputation as one of the most important federal prosecutor shops in the country.

The State Department released 52,000 pages of Hillary Clinton’s emails as part of a court-ordered process. Here's what else we learned from the publicly released emails. (Monica Akhtar/The Washington Post)

The district is home to the CIA and the Pentagon, and its prosecutors often find themselves handling terrorism and national-security cases, including the Moussaoui trial.

The office is led by Dana Boente, a veteran federal prosecutor who U.S. Attorney General Loretta E. Lynch earlier this year called one of the Justice Department’s “consummate utility players.” In addition to the prosecution of former Virginia governor Robert F. McDonnell (R), Boente also led the public corruption prosecutions of former congressman William J. Jefferson (D-La.) and of former New Orleans mayor Ray Nagin (D) while he was serving a brief stint leading the office in New Orleans.

Anne Gearan and Adam Goldman contributed to this report.