The government's case also contained potentially embarrassing allegations that top Google executives, including co-founder
Larry Page, were told about legal problems with the drug ads.
Mr. Page, now Google's chief executive, knew about the illicit conduct, said Mr. Neronha, the U.S. attorney for Rhode Island who led the multiagency federal task force that conducted the sting. "We simply know from the documents we reviewed and witnesses we interviewed that Larry Page knew what was going on," he said in an interview after the August settlement.
Mr. Neronha declined to detail the evidence, which was presented in secret to a federal grand jury. Other people familiar with the case said internal emails showed Sheryl Sandberg, a former top Google executive who left in 2008 for Facebook Inc., had raised concerns about the ads.
Prosecutors could have used that evidence to argue Google deliberately turned a blind eye to lawbreaking to protect a profit stream estimated by the government in the hundreds of millions of dollars.