The FBI may be able to recover at least some data from Hillary Clinton’s private email server even though there was an attempt to wipe it, two sources with direct knowledge of the process told NBC News on Tuesday.

The FBI is investigating the security of Clinton’s personal server and the thumb drives that contain emails related to her work as secretary of state during President Barack Obama’s first term. The Clinton campaign has previously acknowledged that there was an attempt to wipe the server before it was turned over last week to the FBI.