Once again, the relationship between German companies, their shareholders and their bankers is coming under intense scrutiny. The country where stakeholders really matter, where owners, managers, bankers and employees are all supposed to have a say in the running of their companies, is having a serious attack of self-doubt.
With 15 people, including Paul Hochscherf, KHD's deputy chairman, now under investigation for alleged fraud and embezzlement, a grisly tale appears to be unfolding at the heart of German industry.
The story is becoming an all-too-familiar one, in which only the name of the company in trouble seems to change. Deutsche Bank's image has been badly tarnished in recent years by a series of difficulties involving firms in which it was deeply involved as lender, shareholder or both.
Remember Metallgesellschaft, the engineering and metals group that suddenly discovered huge losses in commodities, and the Schneider property group, whose chairman fled the country when his financial difficulties were discovered? Jurgen Schneider is now in a Frankfurt jail awaiting trial.
Perhaps most serious of all the Deutsche imbroglios, although it was not remotely a criminal case, has been the mess made over the last few years by the management of Daimler-Benz, Germany's most important engineering and aerospace group. Last year it lost a whopping DM5.7bn.
At Daimler's annual meeting last week, Mr Kopper was sharply criticised by shareholders for his role in the fall from grace of a company in which Deutsche owns a dominant 24.4 per cent stake. Indeed, Mr Kopper is head of Daimler-Benz's supervisory board, and shareholders took the not unreasonable view that he ought to have known something about the problems earlier.
It is not just Deutsche's reputation as one of the bluest of blue-chip banks that has been damaged. The series of corporate embarrassments involving the bank have also shown up the weaknesses of the once much-praised German system of corporate governance, and shaken the confidence of some of the enthusiasts for importing German methods to the UK.
Many of the Labour Party's stakeholding ideas can be traced back to favourable analyses of the German system for company ownership and control, in which owners share influence with bankers and workers.
Curiously, in the light of his role in recent events, Mr Kopper himself has been one of the sternest critics of the German system, and a debunker of what he sees as the myths that circulate abroad about the dominant role of the banks in German industry.
This may seem odd, given Deutsche's deep involvement with KHD, Metallgesellschaft, Schneider and Daimler, troubled companies where his bank does indeed have a powerful direct interest. But it is a fact that ownership and influence in German industry are much more complex than they seem at first sight.
So are the banking relationships, in a country where a large proportion of the banks are owned by regional and local governments rather than private shareholders.
The idealised and, until recently, influential view of the German system is that bankers ensure that managers in industry have the finance for long-term investment and are shielded from the short-term pressures that stock markets bring to bear on British and American companies.
They exercise their benevolent influence at two levels: by sitting on supervisory boards and by supplying finance to the executive management.
Colin Mayer, an Oxford professor and one of the leading researchers in the area, pointed out in a paper last week for the left-of-centre Institute of Public Policy Research that major involvement of the banks in German companies in fact applied to only a small sector of German industry.
The reality is that there are high levels of concentration and control of German companies both by family shareholders and by other companies that own stakes, rather than by banks.
Indeed, it is beginning to look as if the question of bank involvement in German industry is something of a red herring. The significance of Deutsche Bank's problems is that it has fallen down in its role as a large shareholder rather than as banker to the companies in trouble.
The lessons have not been overlooked in Germany. Managers and shareholders are now looking abroad for new ideas to help them overcome the rigidities and inefficiencies of their own system.
At the heart of German corporate governance is the two-tier board. The top tier, or supervisory board, is drawn from a variety of interests, including bankers, shareholders and employees. Since the supervisory board knows the company better than outsiders, it should in theory be in a better position than anyone else to monitor the performance of management.
The case for the German system is that it avoids what one enthusiast called "the expensive absurdity" of having to wait for a hostile takeover bid to get anything done about a management that has gone wrong. But after Daimler-Benz, it is hard to take this line of argument very seriously.
There was, of course, never any likelihood of the Conservative government importing two-tier boards to the UK, since opposition to the idea is firmly entrenched throughout British industry.
And despite the rhetoric from the Labour Party about a stakeholder society, there seems little inclination to force-feed British industry on German methods, and the earlier enthusiasm among some of the party's policymakers has been discarded.
Alistair Darling, the City spokesman, made clear in a speech last week that Labour was now inclined to build on the British tradition and not try to import German patterns for running companies. In other words, Labour has backed away from radical legislation on corporate governance.
British companies may not be run any better than their counterparts in Germany, but cases such as KHD make it hard to believe they are significantly worse. As Professor Mayer suggested, the stakeholder bandwagon may even be getting under way in the UK just at the wrong moment.
If anything the flexibility of the British system for running companies, with its single-tier boards, powerful executive managements and widely dispersed shareholdings, may have some special advantages of its own at a time of accelerating technical change and competition.