In this case it might not be imposeible. A man might tell a lie, but rarely does he do so by writing an eleven page report with lots of names and details. Yes, there might be exaggerations or even lies, but he details a lot of events. Much of it can be collaborated.
One small bit, the NCR included the following in their article:
"The Register has independently confirmed that the allegations against McCarrick were certainly known to Benedict, and the Pope Emeritus remembers instructing Cardinal Bertone to impose measures but cannot recall their exact nature. "
I expect there are already many reporters working on the details.