Mueller has the original, along with the rest of Comey's contemporaneous notes.
The date of the memo is irrelevant - the contents were neither classified nor privileged. There is no law that makes all unclassified information subject to Executive Privilege, and the memo was his personal recollection of what was said. As such, it's not "government property", unless you believe in the "1984" concept that the state owns everything you think. |
