The IT firm hired by Clinton to oversee private server was reportedly 'a mom and pop shop'
Clinton's unusual email system was originally set up by a staffer during her 2008 presidential campaign, replacing a server used by her husband, former President Bill Clinton.
Before handing it over to Platte River in 2013, Clinton reportedly sent the server to a data center in New Jersey to be wiped of any sensitive information, according to The Washington Post.
In March, Clinton turned over approximately 55,000 pages of work-related emails for the State Department to make public after facing criticism for exclusively using a private server during her time as secretary of state.
She did not break any State Department rules with the arrangement, but critics have noted it makes public-record keeping more difficult and opens up questions about vulnerabilities to her system. Clinton also deleted about 31,000 pages of emails that she says were personal.
It is unclear whether it was fully erased before it was turned over to the FBI earlier this month. The nature of her server means there might still be ways for investigators to recover old data.
"A hard disk drive is very difficult to manipulate," computer scientist Darren Hayes, director of cybersecurity at Pace University's School of Computer Science and Information Systems, told The Associated Press.
"Once you get your hands on a hard drive, there's a lot you can recover."
Files that are deleted from a disk can be recovered from the hard drive, he noted, and data deleted from the drive altogether may still leave fragments that can be accessed with enough digging.
"They may have deleted a lot of data, but there's a lot of data that a good forensics team would be able to recover," Hayes said.
"Nearly all [FBI] investigations are assigned to one of the bureau's 56 field offices," The Times said.
"But given this inquiry's importance, senior F.B.I. officials have opted to keep it closely held in Washington in the agency's counterintelligence section, which investigates how national security secrets are handled."