WASHINGTON — A wide-ranging government investigation of corrupt overseas marketing practices by drug and device makers scored its first major victory Friday when Johnson & Johnson admitted bribing European doctors and agreed to pay $70 million in civil and criminal fines.

Intriguingly, prosecutors said that Johnson & Johnson had provided “significant assistance” in their investigation of others in the industry, resulting in a reduced criminal fine for the health conglomerate. At least a dozen other major drug and device makers are under investigation for similar crimes.

A criminal complaint filed by the Justice Department against a Johnson & Johnson subsidiary that makes knee and hip implants quoted internal company e-mails as stating that providing “cash incentives to surgeons is common knowledge in Greece,” and that, were the company to stop paying bribes, “we’d lose 95% of our business by the end of the year.”

In a written statement, the company said that it originally reported its illegal marketing activities to the government in 2007. “We are deeply disappointed by the unacceptable conduct that led to these violations,” said William C. Weldon, the company’s chairman and chief executive. Indeed, Johnson and Johnson’s admission appeared to have set off the industrywide inquiry.