Wednesday, August 19, 1998 Published at 09:12 GMT 10:12 UK
Starring role for Kenneth
The Kenneth Starr investigation has taken four years and covered almost every aspect of President Bill Clinton's life. The BBC's Claire Bolderson reports.
Mr Starr has taken on a series of investigations into the president, his private life and business dealings.
President Clinton's testimony before the Grand Jury will mark the climax of Mr Starr's four-year investigation.
Mr Starr's work began as an inquiry into whether Bill Clinton, as governor of Arkansas, his wife and their friends broke the law in the 1980s when their Whitewater land investment scheme failed.
The allegations of financial impropriety first surfaced during the 1992 presidential election campaign.
Mr Starr was appointed to take over the investigation in 1994. But his inquiry soon expanded in scope.
He started looking into whether the White House - and Mrs Hillary Clinton in particular had obstructed the investigation.
It was only at the beginning of this year that Mr Starr opened an investigation into the president's sexual conduct.
The move came after allegations surfaced, during the course of the harassment case brought by Paula Jones, of a sexual relationship between Mr Clinton and Monica Lewinsky.
In every instance, Mr Starr has had to get the approval of the Attorney General, Janet Reno, a Clinton appointee, before launching a new inquiry.
He cannot just decide to expand his investigations when he feels like it.
Nevertheless Mr Starr has been heavily criticised by Mr Clinton's supporters for conducting what they say is a witch-hunt inspired by the prosecutor's close ties to the Republican Party.
They point out that in all the investigations Mr Starr has been unable to accuse President Clinton of any wrong doing, though he has had limited success in prosecuting some of the president's oldest friends.
Whether Kenneth Starr has more luck this time will not be known until he presents his report on the investigations to Congress, something that is expected by the end of next month.
After that, it is up to Congress to decide how to proceed.