Apparently government prosecutors withheld evidence from defense attorneys.
The judge in the Stevens case has repeatedly delayed sentencing and criticized trial prosecutors for what he's called prosecutorial misconduct. At one point, prosecutors were held in contempt. Things got so bad that the Justice Department finally replaced the trial team, including top-ranking officials in the office of public integrity. That's the department's section charged with prosecuting public corruption cases.
Interesting that prosecutors in a republican administration were accused of prosecutorial misconduct during a trial against a Republican Senator.