The finance chief of Zurich Insurance, Pierre Wauthier, named chairman Josef Ackermann in his suicide note, the company confirmed on Friday as it pledged to investigate whether he had been put under undue strain before his death.
The insurer has been thrown into disarray since company veteran Wauthier was found dead at his family's lakefront home on Monday and the subsequent resignation of former Deutsche Bank boss Ackermann three days later.
Ackermann, one of Europe's top financiers, quit after Wauthier's family shared the contents of the letter with senior executives at the firm, a source told Reuters. Wauthier explicitly blamed Ackermann in the note for putting him under pressure, said the source, who declined to be named because of the sensitivity of the subject.
Ackermann has described the allegations as "unfounded" but said he would leave to avoid damaging Zurich's reputation. He took over as chairman last year. The insurer said Ackermann had made a personal decision to leave.
Sources said Ackermann and Wauthier had clashed ahead of the company's second-quarter results in August over how they were presented.
Wauthier, finance chief since 2011, mentioned the presentation of the results in his suicide note, a company source added.
In a conference call with investors, the company said there was no link between Wauthier's death and Zurich's financial performance.
"We stand by everything we said at the half year," Chief Executive Martin Senn said.
Acting Chairman Tom de Swaan said the company would investigate the circumstances leading up to Wauthier's death.
"The board sees it as its prime responsibility to look into the question as to whether there was undue pressure placed on our CFO," he said, adding that he was not aware of any inappropriate behaviour by Zurich's board members.
Ackermann's abrupt departure comes on top of a period of flux among Zurich Insurance's upper echelons. Its life insurance chief Kevin Hogan left two weeks ago to join AIG as head of consumer insurance and former general insurance head Mario Greco quit a year ago to lead Italian insurer Generali.
"The board is well aware of the need to strengthen the management team, and I consider this to be our top priority," said de Swaan, who was vice chairman under Ackermann. "Our focus is on ensuring the continued stability of the company."
(Read more: Zurich chairman resigns over CFO's apparent suicide)
The company has set up a telephone hotline for employees shaken by the death of Wauthier, a married father of two.
Shares in the group, the worst performing insurance stock in Europe over the past six months, rose over 1.5 percent after the conference call, snapping a four-day losing streak, with investors saying Ackermann's departure would not derail things.
"Ackermann has not been there for a long time. He's not the architect of anything, and this is not a company in a big transition," said one Top 20 shareholder.