Hillary Clinton in her ad "Family Strong." YOUtuBE The IT firm hired by Hillary Clinton to oversee her private server has told ABC it is "highly likely" a backup copy of the server was made, meaning any emails Clinton deleted before she handed the server over to investigators may still be accessible.

Being able to access the deleted emails via a backup server would most likely make investigators' job much easier, cybersecurity expert Alex McGeorge of Immunity Inc. told Business Insider on Friday.

"The reason you back up a server is fairly straightforward, and it would be standard practice to do so," McGeorge said.

"There's a lot they [investigators] can learn from the server, but not having the backups would probably make that job much more difficult."

Having access to the server's backups could also give investigators "a better timeline," McGeorge said, and allow them to see whether her private account was ever breached by hackers.

ABC News chief White House correspondent Jonathan Karl said the firm hired by Clinton in 2013, the Denver-based Platte River Networks, said it was "cooperating with the FBI.”

Clinton says she deleted roughly 30,000 emails off of her server that were "personal" in nature before handing over another 30,000 emails to the State Department.

"I was permitted to and used a personal email and, obviously in retrospect, given all the concerns that have been raised, it would have been probably smarter not to," she told Iowa Public Radio last week. "But I never sent nor received any classified email, nothing marked 'Classified.' And I think this will all sort itself out."

But authorities sifting through the emails say they have reportedly found more than 60 emails containing classified information, though it's mostly at low levels. Those 60 emails did not include two emails discovered by the intelligence community's inspector general, Charles McCullough III, which allegedly contained information classified as Top Secret/Sensitive Compartmented Information, the government's highest levels of classification.

Platte River "is not cleared" to have access to classified material, Cindy McGovern, chief public affairs officer for the Defense Security Service, told The Daily Caller.

Consequently, the possibility that any sensitive information was stored on the server while it was under Platte River's oversight was "troubling," McGeorge said.

"The fact that Platte River is not a cleared contractor is largely irrelevant, since they were handling what should have been unclassified email," McGeorge said. "That classified email may have been received by a server under their control is troubling, and they may have been less equipped to deal with it."

U.S. Democratic presidential candidate Hillary Clinton speaks at the Iowa Democratic Wing Ding dinner in Clear Lake Thomson Reuters Clinton's unusual email system, currently under investigation by the FBI, was originally set up by a staffer during Clinton's 2008 presidential campaign. It replaced another private server used by her husband, former President Bill Clinton.

The new server was run by Bryan Pagliano, who had worked as the IT director on Hillary Clinton's campaign before joining the State Department in May 2009. In 2013 — the same year she left the State Department — Clinton hired Platte River to oversee the system.

"My big issue here is do you want a small firm with little/no government experience or contracting (according to what's being reported) and no stated security expertise to be in charge of the email system for our secretary of state?" McGeorge said.

"That is fundamentally ridiculous."

There is no evidence that Clinton broke the law, but her campaign is concerned nonetheless.

"They're worried about it," a longtime Clinton adviser and confidant told The Washington Post last week. "They don't know where it goes. That's the problem."