Gribkowsky's credibility is a crucial element of the proceedings, as the former BayernLB risk officer was jailed for receiving Ecclestone's $44 million, allegedly as a bribe to influence the sale of F1's commercial rights.
A BayernLB colleague, however, described some of what Gribkowsky routinely said as coming from "the fantasy world". DPA news agency said the witness worked closely on F1 matters with Gribkowsky.
The witness recalled a dinner at which Gribkowsky apparently declared: "I feel as though he (Ecclestone) sees me as an adopted son and wants to groom me as his formula one successor".
Another Gribkowsky tale told of an Ecclestone suitcase filled with $20 million, although subsequent calculations showed that it is impossible to fit that amount of cash in a suitcase.
The BayernLB colleague explained: "Dr Gribkowsky sometimes had days when he told such things. These were the days that I had to switch off."