The former chief financial officer of Zurich Insurance left a suicide note implicating the group's then chairman Josef Ackermann in his death, the insurer said.
Zurich confirmed the existence of the note after Mr Ackermann dramatically quit on Thursday in the wake of the death of Pierre Wauthier, saying he had "reasons to believe that the family is of the opinion that I should take my share of responsibility".
In a conference call aimed at reassuring investors, Zurich's stand-in chairman Tom de Swaan acknowledged there had been frenzied media speculation over whether there had been a "letter left" by Mr Wauthier.
"We were informed that such a letter exists and we are aware of its contents," he said. "It is correct that it relates to the relationship between Pierre Wauthier and Josef Ackermann."
Mr de Swaan said: "It would be inappropriate for me to elaborate on it. It's a very difficult situation especially for the family and friends of Pierre Wauthier, and we all need to respect their privacy during this difficult time. We all deeply regret his passing, which was completely unexpected."
He said that "the board sees it as its prime responsibility to look into the question of whether there was undue pressure placed on our CFO. Let me be absolutely clear: the board and management of Zurich take corporate culture and behaviour very seriously."
Mr Wauthier, 53, who was married with two children, was found dead on Monday at his home outside Zurich. On Tuesday police said he appeared to have taken his own life.
His widow, Fabienne Wauthier, is said to have accused Zurich's management of driving her husband "into a corner" and that Mr Ackermann's "tough management style" had put Mr Wauthier under insufferable pressure.
Mr de Swaan said Mr Wauthier's death had cast a "shadow" over the company but stressed: "From my own personal perspective I am not aware of any behaviour that would be inappropriate in a board setting.
"The Zurich management team has the board's full support and we fully recognise that the recent developments have been extremely unsettling and our focus is on ensuring the continued stability of the company."
He added: "The board is well aware of the need to strengthen the management team and I consider this to be our top priority."
Mr Ackermann, 65, took over as chairman of Zurich last March after a decade at the helm of Deutsche Bank.
He has a reputation for being a hard task master, with reports suggesting he had come in to "shake up" Zurich.
One insider was quoted, saying: "Ackermann did not become chairman at Zurich in order not to change anything."
In his statement on Thursday, Mr Ackermann appeared to deny that he had placed Mr Wauthier under intolerable pressure, saying that, whatever allegations the family was making, they were "unfounded".