Nice to see this thread rolling along
It's not really PD as they quit rather than being fired, but still.
Recently we had an employee give notice, nothing unusual they sat down with the boss and it was all very civilized, but then towards the end of his notice period things began unravelling. He began disappearing into secluded rooms during work hours with his mobile phone to have very private conversations which would last anything up to an hour.
He stopped passing on information, when his supervisor asked him for some documents he had sent to a client he stalled on providing them for a day and a half and when he did supply them they were only half completed. He started doing strange things like, if I sent an email to a client giving them a timeline for delivery of their purchase, he would immediately send them an email (we are on the same email group so he saw all emails in and out of this group) directly contradicting what I had just told them.
He refused to tell us what he was going to do next, which he doesn't have to do, but we found out he was trying to coerce other members of staff to leave our company and join another one, which is specifically forbidden under the terms of his contract. When this was pointed out to him he flatly denied it despite the proof being placed in front of him.
I was away for the grand finale, but I heard through the grapevine that he called in sick on the Monday, came in on the Tuesday only in order to go to the pub for his 'farewell' lunch, not that this matters as all his tasks had been reassigned, but apparently he was unwilling to even pick up the phone, and then after he left behind his company laptop and all of his files the IT guys discovered that he had spent his final afternoon changing ALL his passwords, for his email, his laptop, his calendar and so on and walked out without telling anyone he had done so. No doubt he thought he was very diabolical but it was a short process for the IT department to simply reset the passwords and shut down his access.
We work in a small-ish industry, everyone knows everyone, so burning your bridges is inadvisable - and word through the grapevine is that the job he left us for has now fallen through, so I bet he's regretting his 'cleverness' now that he's probably going to have to contact us to ask for a reference. Not that we would trash him of course, his work throughout his employment was satisfactory, but (as the boss said) we would have to mention that his notice period was a little "difficult".