The secretive world of Swiss banking has been rocked by a wild scandal involving spies, a suicide, and a clash at a cocktail party.

Credit Suisse hired private investigators to spy on Iqbal Khan, its former head of wealth management, after he feuded with CEO Tidjane Thiam and left for the bank's local archrival, UBS, earlier this year.

The fiasco has culminated with the resignation of both the Swiss bank's COO and Head of Global Security, and the death of the contractor who hired the spies to follow Khan.