The character and experience of the prosecutor and your attitude toward him are critical. You can usually find out which prosecutor is heading up an investigation by looking at the bottom of any grand jury subpoena your client, his company, or another witness receives. Failing that, you can always call the United States Attorney's Office to get this information. Remember that in a white collar case the AUSA is heading up the entire investigative effort, not just passively sitting back and receiving an offense report from a law enforcement agent. As a general rule, you catch more flies with honey.
Jerks have a tendency to get their clients indicted.
While being nice will not prevent the indictment of a plainly culpable client, it can actually make a difference in a close case. Prosecutors enjoy tremendous discretion in deciding who and what to charge. Needlessly hacking them off might make you look or feel like a hot shot, but is seldom beneficial to the client. Being courteous and professional with the AUSA can also positively affect many important non-charging decisions, such as whether your client will be allowed to turn himself in for an arrest, as opposed to being handcuffed in his boxer shorts in front of all the neighbors at six in the morning. There is an exception to the catch more flies with honey rule.