She has kind of a crazy smile herself. My wild guess is she was away on vacation when her patient went berserk. He felt abandoned and this pushed him over the edge
There were stories that his 'girlfriend' had dumped him.
Maybe he had a 'thing' for his psychiatrist, and your 'wild guess' falls in line.
He was being thrown out of his apartment, he had no job, and his 'girlfriend' psychiatrist 'dumps' him (let's him know she's not interested) and then goes on vacation.