Just so you know, I didn't hire this person from the outside--we became friends through working together, and she worked here before I did. She had been hired by someone who was long gone, and there had been several reorganizations, so my boss was   put in charge of her section, and he simply accepted that everyone had the background that they claimed.

When I found out, I did tell him. It was my choice as to how to deal with it, though, and everything was handled confidentially. No one outside the chain-of-command knew what happened.
As near as I can tell, she took advantage of this "confidentiality ". For a reference from our office, she apparently had the new employer contact a manager who had taken a leave of absence before her problem came up and so hadn't been told about what happened, and didn't know anything about her job performance.

I heard about this through the office grapevine.As always, there were a few people around who knew what was going on the whole time, but kept it quiet.

What was she thinking about when she told me? I don't have any idea at all. After she left, we discovered a lot of problems that she had been keeping under wraps. Maybe she had had enough and was just looking for a way out. If I knew then what I know now, I would have given it to here.