Dunbar, a former head of global capital markets, is to leave the bank at the end of the month, sources said.
News of his departure from Deutsche, which he leaves after 16 years, was revealed internally on 25 March but only emerged externally yesterday.
Four years ago Dunbar, along with three Deutsche colleagues, was part of a high-powered team of investment bankers that advised the government and the then chancellor Alistair Darling about the financial crisis.
Dunbar took up the role of head of client franchise development last June as part of a sweeping overhaul of management after Anshu Jain – former head of the investment bank – and Juergen Fitschen took over as joint-chief executives.
He leaves the bank at the end of April.