The Chief Suffic Group, Chief Officer Pierre-Olivier Bouée, resigned after an internal probe found that he ordered the bank's former wealth manager to oversee private investigators without discussing it with CEO Tidjane Thiam or other senior bank officials.  His decision triggered a scandal that has surrounded the bank for the past two weeks, triggering an internal investigation into Credit Suisse and addressing Mr. Thiam one of the more unusual challenges he has encountered at the bank.
Bouée, part of Mr. Thiam's inner circle of top management, takes effect immediately, the Swiss bank said Tuesday as it announced the findings of the probe.
"The Board considers that the mandate for observing Iqbal Khan was erroneous and disproportionate and has resulted in serious damage to the bank's reputation," it states.
chief of global security services to start Mr. Khan's observation.
The bank said Bouée made the surveillance decision alone, without discussing it with Mr. Thiam or other directors.
"The Homburger investigation did not identify any indications that the CEO had approved the observation of Iqbal Khan, nor did he realize it until September 1
Questions about whether the supervised surveillance would threaten Mr. Thiam's position as CEO should be decided, board chairman Urs Rohner said Tuesday, saying the board was confident of investigations no mention that Mr. Thiam did not play a role in the embarrassing events, based on interviews and a review of private communications.
No evidence was found to suggest that Mr. Khan was trying to lure employees or clients, it stood. The bank's head of global security services also withdrew.
Mr. Bouée will be replaced as chief operating officer by James Walker, who has held several roles in the bank, including chief financial officer for the US subsidiaries.
Mr. Khan has joined the Swiss bank UBS Group AG, where he is scheduled to begin work on Tuesday. Mr. Khan negotiated the unusually short so-called gardening with Mr. Rohner, also without Mr. Thiam's involvement, The Wall Street Journal reported earlier, quoting people familiar with the matter.
17. In September in Zurich, Mr. Khan discovered an investigator who was following him and went to take photos of the investigator and his car, according to people familiar with the incident. Khan filed a complaint with police, and Zurich prosecutors last week said "temporary arrests" had been made as part of the resulting probe. The prosecutors said they opened a criminal investigation into possible abuse and threat based on Mr. Khan's complaint.
A consultant who helped the bank hire investigators to track Mr. Khan died in an apparent suicide last week, a Switzerland lawyer said Monday.
Credit Suisse board members confirmed his death and expressed his condolences at a press conference on Tuesday.
Despite the bank's shares losing about half its value since Mr. Thiam took over in 2015, major shareholders have largely welcomed the restructuring. He quickly increased Credit Suisse's focus on selling investment and trading products to ultra-healthy customers. He promoted Mr. Khan, hired in 2013 as chief financial officer for the wealth management arm, to run most of that business internationally.
The relationship between Mrs. Thiam and Khan has deteriorated markedly over time, said people who know them. The magazine and other outlets reported tensions between the two men in recent days, especially in the past year, which were partly triggered by Mr. Khan's growing ambitions.
They also flared near the home: In a tinted neighborhood overlooking Lake Zurich, Mr. Khan and his family remodeled a house next to Mr. Thiam's. The two exchanged words at a party in January this year at Mr. Thiam's home after Khan raised concerns with Mr. Thiam's girlfriend about trees on the Thiam property, according to people familiar with the matter.
Mr. Khan later had talks with rival banks, including minor rival Julius Baer Group Ltd., about leaving Credit Suisse for another job, clashing with Credit Suisse's beliefs that he wanted more power or could look to leave, people known with the case.  Credit Suisse July 1 said that Khan would leave the bank to pursue his career elsewhere. In a statement, Mr. Thiam wished him good luck. In late August, UBS appointed him as head of asset management.
Investigo, a small detective company in Zurich, said in a statement issued to Credit Suisse and the Swiss authorities last week that the firm's mandate was to follow Mr. Khan remotely and take pictures of people he met.
—Pietro Lombardi contributed to this article.
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