The New York Times has this article that talks of Rudolph Giuliani's efforts to intervene with W.D. Va. U.S. Attorney John Brownlee, on behalf of Giuliani's then-client Purdue Pharma, manufacturer of OxyContin:
"They figured Mr. Brownlee, a younger federal prosecutor, would look up to Mr. Giuliani, who became a legend as a United States attorney in New York.
Between June and October 2006, Mr. Giuliani met or spoke with the prosecutor on six occasions. During those conversations, Mr. Giuliani was cordial but pointed in arguing against what he felt were flaws in the case.
Mr. Brownlee would not change course, though, even when the Purdue legal team appealed, unsuccessfully, at the 11th hour to his superiors at the Justice Department in Washington.
In October 2006, Mr. Brownlee told Mr. Giuliani and Purdue that he expected to ask for a grand jury indictment by the end of the month. Plea discussions ensued and Mr. Brownlee ultimately agreed that the three executives would not have to do jail time."
The article also cites Tazewell County Commonwealth's Attorney Dennis Lee: "Dennis Lee, the Virginia state prosecutor for Tazewell County, an area hard hit by OxyContin abuse, said he was stunned several years ago to learn that Mr. Giuliani was working for Purdue. He had a favorable impression of Mr. Giuliani, he said, and a poor opinion of the company, which he said had played down and dissembled about its drug’s problem."
PointofLaw has this post, which explains part of the context of the criminal investigation, suggesting that the government holds all the cards in this area even more than usual.