British defence minister Mr Geoff Hoon and media adviser Mr Alastair Campbell face tough cross-examination today in the final week of the Hutton inquiry.
The inquiry into the suicide of weapons expert Dr David Kelly has already wreaked political damage on Mr Tony Blair's government.
Mr Campbell and Mr Hoon are likely to be asked about the government's handling of Dr Kelly after he admitted to his bosses that he may have been the source of an explosive BBC report in May accusing Mr Blair's government of "sexing up" the dossier.
Mr Hoon, singled out by British media as a likely government fall guy over the Kelly affair, has played down his role in the strategy to name the scientist.
But the inquiry has shown he attended a meeting where officials at his ministry agreed to confirm Dr Kelly was the suspected BBC source if his name was put to them by journalists.
He also overruled advice from his top civil servant to shield Dr Kelly from a hostile parliamentary grilling just days before he took his life. Lawyers for Dr Kelly's family have their first chance to question Mr Hoon over both issues today.
Ahead of today's cross-examination, an opinion poll found that one in three voters thought Mr Hoon should resign over his role in the affair.
Intelligence chiefs have conceded to Lord Hutton that a warning in Mr Tony Blair's September 2002 dossier that Saddam Hussein could use weapons of mass destruction at 45 minutes' notice was based only on information about short-range and relatively small-scale battlefield munitions. That intelligence came from a single source, quoting an Iraqi military officer.
Counsel to Lord Hutton's inquiry, Mr James Dingemans, will deliver a closing statement on Thursday. But Lord Hutton warned last week there was no real prospect of delivering his final report in October.