This, however, was McNamee's initial meeting with Assistant U.S. Attorney Daniel Butler, who is presenting evidence to the federal grand jury determining whether Clemens should be charged with lying to Congress when he denied using performance-enhancing drugs.
McNamee did not speak to reporters, only shaking his head when asked if he would comment, as he arrived Friday morning at the U.S. Attorney's office in Washington accompanied by his lawyers, Richard Emery and Earl Ward.
"It went very well," Ward said later in a telephone interview, while the trio traveled back to New York by train. "I think there will be additional meetings. They told us they would get in touch with us."
A day earlier, and only a few blocks away, the convicted steroids dealer who led the feds to McNamee - former New York Mets clubhouse attendant Kirk Radomski - appeared at the federal courthouse where the grand jury examining Clemens' case meets twice a week.
McNamee and Radomski figure to be among Butler's primary witnesses against Clemens, whose lead lawyer, Rusty Hardin, did not respond to requests for comment.
In addition to lead prosecutor Butler, Friday's meeting included the top fraud and corruption prosecutor in his office and two federal investigators. Federal agent Jeff Novitzky - who has been at the center of the BALCO and Barry Bonds cases - participated via telephone.
Neither Ward nor Emery would describe the questioning.
"All I can say about the substance of the discussions is that they were very well prepared," Emery said. "They are pursuing lines of investigation that are extremely probative and are going to be extremely useful in this investigation. They are doing a heck of a good job."
McNamee's lawyers said they have not been told when their client, a former New York police officer, will speak to the grand jury.
"Brian has cooperated from the beginning of this investigation, and he was thorough and careful and well-prepared," Emery said. "There's nothing 'old hat' about it. He takes his responsibility as a witness extremely seriously."
Friday's meeting was preparation for McNamee's grand-jury appearance.
McNamee, once close friends with the former baseball star, has turned over to government agents syringes, vials and other items his lawyers said would link Clemens to drug use. Clemens' camp has called it "manufactured" evidence.
McNamee's allegations that Clemens had used illegal performance-enhancing drugs first surfaced publicly in Mitchell's 409-page report on doping in baseball that implicated seven MVPs, 31 All-Stars and identified 85 players to differing degrees.
McNamee repeated his account last year under oath to congressional investigators and at a public House hearing that was prompted by Clemens' denials of what was in the Mitchell report. Clemens testified that he did not use performance-enhancers.
"I have never taken steroids or HGH," the 354-game winner told Congress in February.
Two former teammates of Clemens, Andy Pettitte and Chuck Knoblauch, both acknowledged to Congress that McNamee was correct when he said they used performance-enhancers.
The he-said, he-said nature of the sworn testimony given to Congress by McNamee and Clemens prompted lawmakers to ask the Justice Department to investigate whether the former pitcher lied. The case was brought before a grand jury after an 11-month FBI investigation.
Clemens last pitched in the major leagues for the New York Yankees in 2007. Another of his former teams, the Houston Astros, has confirmed that Clemens will not be working out with their minor leaguers at spring training in Florida this year, something he did do just weeks after testifying on Capitol Hill.
