Tens of thousands of emails once housed on former secretary of state Hillary Clinton's private computer server were moved to another device after a Colorado company took possession of the device in 2013, leaving open the possibility that copies of messages Clinton later chose to delete might still exist.

The FBI seized the server this week in a stunning move, signaling a new intensity in the investigation into whether Clinton knowingly send or received top-secret classified information through her private address while she was America's top diplomat.

Bloomberg reported Thursday night that Barbara Wells, an attorney for Platte River Networks, Inc., confirmed that while the server hardware now controlled by the FBI 'is blank and does not contain any useful data,' its contents could still be safe and sound elsewhere.

That's because the server's messages were 'migrated' to another server that still exists, she said, before ending the Bloomberg interview without specifying where that device is located and who owns it – only that her company no longer has it.

THE WHO DID WHAT, NOW? Clinton's deleted emails, numbering more than 30,000, may still exist because the IT company hired to manage her server made a copy elsewhere – but it's unknown whether that copy is gone

Platte River Networks' attorney said the company migrated Clinton's server data to another device after it took possession of her machine in 2013

'The data on the old server is not now available on any server or device that is under Platte River's control,' Wells said.

A Monmouth University poll, released Wednesday, shows that 52 per cent of American voters believe the federal government should pursue a criminal investigation in the case.

That number might soon grow: The Monmouth survey was conducted before the server landed in the hands of law enforcement, along with three thumb drives held by her lawyer that reportedly contain raw copies of 30,490 emails she handed over to State Department investigators late last year.

A random sample of 40 of those messages examined by U.S. Intelligence Community Inspector General Charles McCullough's office included two that contained information later classified as 'top secret.'

Another 31,830 emails, however, were deleted at Clinton's request after her staffers sifted through them and determined that they were personal in nature.

Republicans on Capitol Hill cried foul in March after she casually acknowledged during a combative press conference that she had made that decision without oversight from anyone in government.

Clinton and her presidential campaign have insisted, most recently in a 4,000-word explanation this week, that those messages were not work-related.

Clinton used an '@clintonemail.com' address exclusively during her four years as secretary of state instead of keeping her correspondence on a '@state.gov' account. That made it more likely that her emails were open to hackers, and made it impossible for the State Department to keep a complete archive.

An aide to a Republican member of the Senate Intelligence Committee told DailyMail.com that McCCullough has been pressed to give Congress regular updates if more classified information is discovered.

'We're not letting go of this,' he said, while denying that going after Clinton was a political exercise.

'I don't care if it's Hillary Clinton or Ted Cruz,' he said, naming a Texas senator who is running for president, but who is not a committee member. 'If we don't aggressively follow this wherever it leads, what good are we?'

It's not clear if Clinton's long-deleted data actually exists on another machine, even though Wells says it was once moved there.

But even if it's gone for good, the FBI's digital forensic experts may be able to recover some or all of it from the 'clean' Platte River server – depending on the method that was used to 'wipe' it.

Methods also exist to determine if traces of a malicious hack remain behind.

Hard drives store information in large sections that are separate from a 'directory' block – a sort of table of contents that tells a computer where to find each file's many constituent pieces.

NOTHING TO SEE HERE: Clinton told reporters in March that 'I did not email any classified material to anyone on my email; there is no classified material'

When a PC 'deletes' a file, that directory entry is typically the only part that is actually erased. The larger data remain, although the space where they reside is made available for other files.

So sometimes large portions of files can be recovered and reconstructed if they have been overwritten, even though a computer considers the device to be empty.

'Most people don't understand really what it takes to actually delete things from a computer permanently,' Peter Toren, a former computer crimes prosecutor for the Justice Department, told Bloomberg.

'The FBI has had a great deal of training and they're very good about recovering data from computers that people think have been erased or deleted.'