Hillary Clinton wasn’t a newcomer to secret documents when she reached the State Department.

She said she handled classified information as first lady and had regular access to secret documents as a senator, particularly during her six years on the Armed Services Committee — all of which makes Mrs. Clinton’s bungled treatment of the most sensitive information while secretary of state difficult to understand.

“She doesn’t come into this as your average person. She comes in as someone who served on the Armed Services Committee, who has been privy to classified information in the past before she became secretary of state, and, by the way, she was a former first lady,” said Sen. Kelly Ayotte, a New Hampshire Republican who sits on the same committee, and who said she found Mrs. Clinton’s explanation to be incredible.

The latest evidence confounding those trying to understand Mrs. Clinton’s handling of emails comes from the FBI, which released notes of its criminal investigation last week showing the former secretary remarkably unaware of her own classification powers as secretary.

She couldn’t name a single time she’d designated information as classified, said she didn’t worry about the distinction between confidential, secret and top secret information and stumbled when asked to decipher classification marks on some of the messages she sent and received.

Three of her emails had material marked with a “(C)” designating paragraphs that followed as classified.

The Democratic presidential nominee defended herself this week, telling ABC in an interview that most of her emails that contained secret information lacked markings, so it wasn’t clear what the information was.

“There were no headers on the thousands of emails that I sent or received. There just weren’t, and the FBI has not in any way contradicted that,” she told the network. “There were a couple of emails with a tiny ‘C’ in a parenthesis, which did not have a header saying that means ‘confidential’ in this circumstance, and which the director of the FBI has said, and the State Department has said, those couple of emails were improperly marked, even with that. So, yes, I take classification seriously, and I think the record shows that I have.”

The FBI said there were actually three messages, and said it has determined at least one of them contained information that was confidential at the time Mrs. Clinton handled it.

Hundreds of other messages contained information that wasn’t marked at all but was still classified — including a handful of chains that were top secret, with information such as possible targets of U.S. drone strikes — that Mrs. Clinton handled over her nonsecure email server at her home in New York.

Mrs. Clinton said she trusted her aides to get the classification right, and since they didn’t mark those documents, she didn’t think to question them.

Those who have been through classified briefings on Capitol Hill, however, said she should have known better based on that experience alone.

Former Sen. Jim Talent, who served with Mrs. Clinton on the Armed Services Committee for six years beginning in 2003, said when they encountered classified information or had briefings, they had to go into a locked room with staffers monitoring the door. They weren’t allowed electronics, and couldn’t even take their own handwritten notes from the room.

“It’s impossible to go through that experience without being aware that there are strict protocols,” said Mr. Talent, who is now a senior fellow on national security at the American Enterprise Institute.

He said the documents they encountered at the committee would typically be marked classified, and said it was not credible to think she was unaware of those designations.

“Of course you would be told what the markings meant. I can’t imagine anybody being under that misimpression. And no staff would send you anything over an insecure email that was classified, unless they’ve been told to do it or they understood they were supposed to do it,” he said.

Sen. Claire McCaskill, a Missouri Democrat who succeeded Mr. Talent and is now on the same military committee, recalled her own briefing on classified material by her military legislative assistant, or LA.

“There was basically a sitdown with my military LA, who was military, to talk about what was and wasn’t [classified] and how to handle it. And there was some discussion about when we went into classified sessions,” said Mrs. McCaskill, who is a staunch supporter of Mrs. Clinton.

But the senator said she had no concerns about Mrs. Clinton’s failure to recall similar briefings or the instructions provided.

“Because it wan’t a formal thing. It was more of an informal thing, which I’m sure she was briefed by her military LA,” Mrs. McCaskill said.

Sen. Bill Nelson, Florida Democrat, said he hadn’t read the FBI’s notes on its investigation, but said those handling information usually rely on cues to tell them what kind of material they’re dealing with.

“They have a bunch of designations for those that I never memorized, but I saw the letters, I knew it was compartmented, and so I was always very sensitive to that stuff. But if you are getting it over an unclassified computer, you don’t have any reason to think that it is classified,” he said.

Steven Aftergood, director of the Federation of American Scientists’ project on government secrecy, said Mrs. Clinton would have been familiar with handling classified information from her time in the Senate, and would have seen her exposure — and responsibility — grow in the State Department, where she is one of a small list of people given original classification authority at the top secret level.

“At various stages along the way, she would have received briefings on procedures for safeguarding classified information, and she would have signed nondisclosure agreements,” Mr. Aftergood said. “But that doesn’t mean she would be entirely familiar with the minutiae of marking classified documents, which is more of an administrative function.”

Before her time in the Senate, as first lady from 1993 to 2001, Mrs. Clinton did not hold a security clearance. But she did brag in a 2007 interview about having access to classified information nonetheless.

“I had direct access to all of the decision-makers. I was briefed on a range of issues, often provided classified information. And often when I traveled on behalf of our country. I traveled with representatives from the DOD, the CIA, the State Department,” she said in an interview with ABC after a New York Times article reported on her lack of clearance.

At that time, she was bragging about her access in order to boost her 2008 presidential campaign.

Now, however, that access is a political problem — and perhaps still a legal one.

While the FBI said she shouldn’t be prosecuted for mishandling secret information because she was too unsophisticated to understand what she was doing, members of Congress have asked prosecutors to look into whether she lied to Congress about her behavior.

And on Tuesday Rep. Jason Chaffetz, chairman of the House Oversight Committee, asked the U.S. attorney in Washington, D.C., to investigate whether Mrs. Clinton’s aides may have obstructed justice by deleting some 30,000 messages she deemed personal.

Congress had subpoenaed the emails and issued a preservation order in early March 2015, but Platte River Networks, the Colorado company Mrs. Clinton asked to handle her server, wiped the server and backup tapes clean at the end of that month — after hearing from Mrs. Clinton’s lawyers.

Mrs. Clinton dismissed the complaint.

“The FBI resolved all of this,” she told reporters Tuesday on her campaign plane, according to The Associated Press. “Their report answered all of the questions.”

But Trump campaign surrogate Rudolph W. Giuliani, the former federal prosecutor and New York mayor, said the FBI notes undercut Mrs. Clinton’s explanation.

“She is either grossly inadequate to handle confidential information or she is lying,” Mr. Guilliani told reporters in a conference call. “I am guessing it is probably the latter, because I don’t think Hillary Clinton is that ignorant.”

• Seth McLaughlin contributed to this article.

Sign up for Daily Newsletters Manage Newsletters

Copyright © 2020 The Washington Times, LLC. Click here for reprint permission.