I know someone like that. Even when she is caught doing something and there is no doubt she did it, she will deny it. Once, she and her ridiculously younger punk boyfriend vandalized our work place because she was angry over the fact that the boss came in late one night and caught them in the dining room smoking pot, and fired her. She blamed everyone and everything besides herself. She bought a used mattress set that had bed bugs, and tried to tell everyone that someone else in a neighboring apartment brought them in. In a job BEFORE the restaurant (nursing home, where I first met her) she told me she got in trouble for telling a patient to "shut up" rather loudly. She said she didn't and she was being persecuted, etc. Well, I HEARD her do it although I was down the hall at the time and did not know who she was talking to ....