Why did Hillary Clinton delete about 30,000 emails?

Hillary Clinton just made a rather astonishing admission.

At the Tuesday afternoon press conference where she attempted to dismiss concerns about her use of a private email system for official business, Clinton revealed she deleted about 30,000 messages.

She characterized the messages that were erased as personal correspondence and said she had "no reason to save them."

"In going through the emails, there were over 60,000 in total, sent and received. About half were work-related and went to State Department and about half were personal that were not in any way related to my work," Clinton said. "I had no reason to save them, but that was my decision because federal guidelines are clear. ... For any government employee it is that government employees responsibility to determine what's personal and what's work related."

Clinton said she "chose not to keep" the messages and said she expected people would understand her need for "privacy."

"We went through a thorough process to identify all of my work-related emails and deliver them to the State Department. At the end, I chose not to keep my private, personal emails. Emails about planning Chelsea's wedding or my mother's funeral arrangements. Condolence notes to friends, as well as yoga routines, family vacations: the other things you typically find in in- boxes," she explained, adding, "No one wants their personal emails made public. And I think most people understand that and respect that privacy."

Even if all the emails that were erased were indeed personal, the deletion of those messages could have implications for potential investigations into Clinton's communications.

Clinton's emails have been the subject of a growing controversy since a New York Times article published last week revealed she exclusively used a private address on the domain "clintonemail.com" when she lead the State Department from 2009 through early 2013. The Times suggested this may have been a violation of federal recordkeeping regulations.

The former secretary of state and her team have claimed her use of personal email for official business went above and beyond regulatory requirements. At the press conference, Clinton said she and her team engaged in a "thorough process" to identify all work-related emails and turn them over to the State Department.

In spite of these defenses, many Republicans have said they still have questions about Clinton's emails and some have called for her allow an independent arbiter to examine her server. Clinton rejected the idea of an independent investigation at the press conference. And the fact her personal emails were deleted would seem to completely eliminate the possibility an independent arbiter could ever be employed to determine whether she gave the State Department all work-related correspondence.

Clinton's decision to delete her email also could affect the House of Representatives committee dedicated to investigating the 2012 terrorist attack on the US diplomatic compound in Benghazi, Libya. Republicans have been critical of Clinton's handling of the attack and the committee has long sought to obtain her emails.

Last Wednesday, the committee issued a subpoena for Clinton's emails. In a statement about the subpoena, the committee's spokesman also announced that it "issued preservation letters to internet firms informing them of their legal obligation to protect all relevant documents." However, Clinton's decision to delete her emails may have affected what was preserved and could prevent the committee from issuing further subpoenas. A committee spokesperson did not immediately respond to a request from Business Insider asking if they were concerned about the deleted emails.

In addition to closing off these potential investigations, Clinton's decision to delete her emails would also seem to eliminate the chance she could ever make these messages accessible to historians and archivists as many other major figures have.

Clinton hasn't really made her rationale for deleting the personal emails clear beyond saying she "chose" to do so and had "no reason to save them." Her team did not respond to multiple requests from Business Insider asking them to elaborate on why she deleted the messages. However, a written statement Clinton's office distributed following the press conference seemed to attribute the decision to a desire to "ensure the continued privacy" of the messages.

"Government officials are granted the privacy of their personal, non-work related emails, including personal emails on .gov accounts. Secretary Clinton exercised her privilege to ensure the continued privacy of her personal, non-work related emails," the statement said.

Indeed, it seems that even though her communications have attracted the attention of investigators, her mass deletion will ensure they remain private forever.