So, on one winter evening in late 2002, five executives from the telecommunications group met for dinner at a traditional Bavarian restaurant in a Munich suburb. Surrounded by dark wood panels and posters celebrating German engineering, the group discussed how to better disguise its payments, while making sure that employees didn’t pocket the money, Mr. Siekaczek said.

To handle the business side of bribery, the executives turned to Mr. Siekaczek, a man renowned within the company for his personal honesty, his deep company loyalty  and his experiences in the shadowy world of illegal bribery.

“It had nothing to do with being law-abiding, because we all knew what we did was unlawful.” Mr. Siekaczek said. “What mattered here was that the person put in charge was stable and wouldn’t go astray.”

Although Mr. Siekaczek was reluctant to take the job offered that night, he justified it as economic necessity. If Siemens didn’t pay bribes, it would lose contracts and its employees might lose their jobs.

“We thought we had to do it,” Mr. Siekaczek said. “Otherwise, we’d ruin the company.”

Indeed, he considers his personal probity a point of honor. He describes himself as “the man in the middle,” “the banker” or, with tongue in cheek, “the master of disaster.” But, he said, he never set up a bribe. Nor did he directly hand over money to a corrupt official.

German prosecutors say they have no evidence that he personally enriched himself, though German documents show that Mr. Siekaczek oversaw the transfer of some $65 million through hard-to-trace offshore bank accounts.

“I was not the man responsible for bribery,” he said. “I organized the cash.”

Mr. Siekaczek set things in motion by moving money out of accounts in Austria to Liechtenstein and Switzerland, where bank secrecy laws provided greater cover and anonymity. He said he also reached out to a trustee in Switzerland who set up front companies to conceal money trails from Siemens to offshore bank accounts in Dubai and the British Virgin Islands.