Khan’s meteoric success brought him immense financial wealth. He soon bought a piece of property that is adjacent to the home of Tidjane Thiam, the 57-year-old CEO of Credit Suisse. Khan and his wife had the house on their property demolished and began a two-year project to build a new house. But the disruption caused by the large-scale construction project gave rise to a dispute between Thiam and Khan. Their rivalry escalated quickly and prompted the intervention of Credit Suisse board chairman Urs Rohner. However, the dispute between the two men was not resolved, and on July 1 of this year Khan left Credit Suisse. On August 29, Credit Suisse’s rival UBS announced that Khan would co-lead its global wealth management division.

It appears that some Credit Suisse executives were concerned that Khan might try to attract their firm’s customers to his new UBS portfolio. These concerns allegedly prompted Credit Suisse’s Chief Operating Officer (COO), Pierre-Olivier Bouee, to instruct the bank’s security department to keep tabs on Khan. The bank reportedly hired a private investigation firm, Investigo, to monitor Khan’s movements. There was an unexpected turn on September 17, when Khan noticed that he was being followed and promptly confronted an Investigo employee in downtown Zurich. On the same day, the former Credit Suisse star manager filed a complaint with the Zurich office of the Swiss Public Prosecutor.

On September 18, Credit Suisse gave orders to Investigo to stop keeping tabs on Khan. It also launched an internal investigation to evaluate the merits of the decision to spy on Khan. Meanwhile, the Swiss Public Prosecutor’s office announced that it had opened a criminal case on Investigo and had arrested three individuals in connection with the case. On September 24, a private investigator, who is believed to have been involved in Khan’s case, committed suicide. Media reports said the unidentified man was “an external security expert” who mediated between Credit Suisse and Investigo.

On Tuesday, Credit Suisse COO Bouee announced his resignation. Swiss media said the head of the bank’s global security division also resigned. Also on Tuesday, Credit Suisse’s internal investigation found that CEO Thiam had not been involved in the decision to spy on Khan.