Former House speaker Dennis Hastert (R-Ill.) pleaded not guilty Tuesday to charges that he structured bank withdrawals to avoid attracting the attention of federal regulators and lied to the FBI about the transactions. The move added a second round of questions and intrigue to what was already a mysterious and surprise-filled case.

Some might have expected Hastert to appear in court, quickly enter a guilty plea and try to avoid any further public airing of the facts of the case.

After all, in the weeks since Hastert’s indictment became public, reporters have ferreted out information that moves well past what the document disclosed. The indictment mentioned cash withdrawals made over a period of four years totaling “in excess of $1.7 million.” The money was allegedly part of an agreement to pay a person identified only as “Individual A” in the indictment a total of $3.5 million, in order to compensate for and conceal Hastert's prior misconduct against "Individual A.”

Allegations now suggest that Hastert might have made those payments to conceal sexual contact with a student during the time that Hastert was a high school teacher and wrestling coach.

[Indictment of former House speaker Dennis Hastert]

But Hastert pleaded not guilty.

Nancy Gertner, a former federal judge in Massachusetts and now a Harvard University Law School professor who teaches a course on sentencing, said that a guilty plea and plea bargain were always very unlikely Tuesday.

A plea bargain requires negotiations. And negotiations take time. Hastert appears to have very recently switched lawyers, moving from the counsel of his former lobbying firm colleague to the client roster of an experienced white-collar crime lawyer, Thomas C. Green, The Washington Post reported.

[Hastert hires veteran lawyers in Washington and Chicago to defend him on hush money charges]

Green is a lawyer with a list of high-profile clients that include the one-time head of Freddie Mac and a one-time government official who saw a conspiracy conviction related to the Watergate break-in overturned. And Green's level of skill and experience might be needed here. Any attempt that Hastert might make to negotiate a reduced sentence in exchange for a guilty plea will probably be detailed, extended and intense.

First, there is the matter of the actual charges Hastert is facing, the point from which negotiations will actually begin. Federal sentencing guidelines for the two charges Hastert faces include fines, said Jennifer Rodgers, the executive director of Columbia University’s Center for the Advancement of Public Integrity. They also include a penalty of up to five years in prison for the structuring and probation time for lying to the FBI about those bank transactions.

Rodgers worked as a federal prosecutor for more than 13 years, and she said that someone Hastert’s age (73) with no known criminal history might be able to negotiate no jail time or very little. That would not be unusual.

But there are some big ifs here.

Federal prosecutors are guided by federal sentencing guidelines, however, they have some discretion in making sentencing recommendations to the court. So do federal judges as they actually decide whether to hand down prison time.

If the prosecutors consider Hastert’s alleged crimes part of a larger criminal matter, Hastert could face fines and jail time of up to 10 years for the structuring charges. It’s difficult to say with certainty whether federal prosecutors will consider Hastert eligible for this kind of enhanced sentence and will want to begin negotiations there. But it is possible.

Then, there is the matter of Hastert’s alleged sexual abuse of students, crimes that might no longer be subject to prosecution in state court. That combination might not put federal prosecutors in a frame of mind that says, "Let’s give this guy the lightest sentence possible," Rodgers said.

Finally, there’s the matter of what any sentencing briefs and other documents that might become public would disclose. The crimes of which Hastert is accused are directly related to his effort to conceal what the indictment called “wrongdoing.” Hastert and his initial legal team reportedly negotiated the vague and mysterious language in the indictment. Gertner thinks Hastert would very likely want to do the same in any deal that includes a guilty plea.

Of course, keeping the details to a minimum might be what Hastert wants, but prosecutors might want to include some of that information in evidence presented to the court before any negotiated sentence. Federal sentencing guidelines – wrongly in Gertner’s opinion – also allow judges to consider conduct for which the defendant has not been charged before handing down a sentence.

And like Rodgers, Gertner doesn’t imagine that any of these decisions will be made quickly.

In fact, that’s what made Hastert’s not guilty plea the only part of this situation that both women thought should have been fully anticipated. Almost every defendant comes to his or her federal arrangement and enters an initial plea of not guilty.

Then, sometimes, after negotiations, they change their minds.