In Romania, the president is in charge of foreign policy and defence, and names key prosecutors and the chiefs of intelligence services.
He can attest that the judge was there on business, a key point if prosecutors hope to convict Mr. Loughner of the murder of a government official.
The trainer, Greg Anderson, is a key witness because prosecutors say he can authenticate several pieces of evidence, including doping calendars and the results of positive steroid tests.
Mr. Barber will most likely be a key witness for prosecutors, as they build their case against Jared L. Loughner, who is accused of opening fire at Ms. Giffords and others on Jan . 8 killing six people, including Judge Roll, and injuring the congresswoman and 12 other people.
In what was seen as a key test for prosecutors' ability to pursue white-collar crime, Mr. Nacchio was found guilty in April 2007 of using insider knowledge to sell $52 million of Qwest's stock before disappointing financial results sent the company's shares tumbling.
Brumberger's testimony during the campaign finance corruption trial is a key part of prosecutors' efforts to establish the timeline of the affair and efforts to conceal it.
"I think we cannot underestimate the case," said Nancy Paterson, who was a key member of the prosecutor's office until last May.
The testimony of Mr. Fastow underscored a key element of government prosecutors' case against Kenneth L. Lay and Jeffrey K. Skilling, the two former top executives at Enron accused of fraud and conspiracy stemming from its collapse in 2001.
Mr Huang's appointment, like the establishment of the new Anti-Corruption Administration (ACA), demonstrates Ma Ying-jeou's determination to run a clean government.The ACA will report to the Ministry of Justice instead of the president because the ministry is the supervisory agency for all public prosecutors, and the prosecutors play a key role in the investigation and indictment of suspects.
He badgered prosecutors into dropping a key charge even after the man was convicted and called a prosecutor to lobby him, an unusual and improper move.
