By Chris Cillizza, CNN Editor-at-large

(CNN) -- On Monday afternoon, prosecutors in the invasion of privacy case against Missouri Gov. Eric Greitens suddenly dropped it. It was the latest in a series of wild developments surrounding Greitens, a Republican who is charged with blackmailing a woman with whom he had an affair. (Greitens admits the affair but denies any legal wrongdoing.)

I reached out to my friend Jason Rosenbaum of St. Louis Public Radio for the latest update on how big a deal Monday's surprise move is -- and how much trouble Greitens is still in. The answer? A lot, still.

Our conversation, conducted via email and lightly edited for flow, is below.

Cillizza: Prosecutors dropped the case against Eric Greitens on Monday. Why? And was this expected or not?

Rosenbaum: It was a shock to everybody in the courtroom. In fact, before the announcement, jury selection was continuing on at a methodical (and glacial) pace. There was no indication that St. Louis Circuit Attorney Kim Gardner's office was about to drop the case. In a saga that's included lots of twists and turns and drama, Gardner's decision was a legitimate surprise.

The reason for the decision goes back a few weeks. An investigator that Gardner hired, William Tisaby, allegedly made false statements during a deposition about his interview with the woman at the center of this case. Gardner was in the room while the interview was going on -- and Greitens' attorneys contended she didn't do enough to stop Tisaby from perjuring himself. Since Tisaby invoked his 5th Amendment rights against self-incrimination, Greitens' attorneys couldn't question him during the trial about how he gathered facts in the case. Since Gardner was in the room while it happened, so to speak, St. Louis Circuit Judge Rex Burlison decided that Gardner could be called as a witness. According to Gardner's office, that placed the first-term official in "the impossible position of being a witness, subject to cross-examination within the offer of proof by her own subordinates."

Cillizza: Virtually every Republican lawmaker in Missouri has said Greitens should resign. Does yesterday's ruling change any minds or give any of them pause about pushing him out?

Rosenbaum: Republicans were bracing for the possibility of Greitens being found not guilty on the felony invasion of privacy charge. He's accused of taking a semi-nude photo of a woman without her consent, yet Gardner's office did not have that picture in their possession. That didn't necessarily mean a jury wouldn't convict Greitens — especially if the woman's testimony to jurors was convincing. But not having the photo clearly wasn't helpful to Gardner, and it's not Greitens' responsibility to prove her case for her.

With that in mind, Republicans like Rep. Shamed Dogan were emphasizing before Monday that impeachment was not predicated on getting a criminal conviction. "Under that standard, you could have a Gov. Harvey Weinstein or a Gov. Bill Cosby up until last week or a Gov. O.J. Simpson," Dogan told me last week.

The special session to potentially consider Greitens' impeachment begins on Friday. But before Gardner's announcement, some Democrats were concerned that not trying to throw [out] Greitens earlier would have consequences. There's an expectation that Greitens' political team will spend a lot of money trumpeting Monday's news, which may affect how Republicans feel about impeachment. "That messaging is going to be back in the bases of all these Republicans," said state Rep. Peter Merideth (D).

Ciliizza: Where do things go from here? Is Greitens out of the woods?

Rosenbaum: Greitens still faces a treacherous political road. It only takes 82 House members to impeach him, and Republicans hold 114 seats. That means only a small percentage of the GOP caucus has to join with House Democrats for that to happen. In the event of a House vote for impeachment, it will be up to a panel of judges to decide if Greitens is booted from office.

On the legal front, Greitens still faces a felony charge for using a fundraising list from a veterans charity he helped found for political purposes. And Gardner said she plans to refile the invasion of privacy case with a special prosecutor. Greitens' attorneys doubt that any other prosecutor will pick the case up, especially if there's no photo that would make it easier to convict him. "There's not going to be a special prosecutor. Because any prosecutor would look at these facts, recognize the facts and never go forward," said Greitens attorney Scott Rosenblum.

Cillizza: There are any number of allegations against Greitens -- from the blackmail to campaign finance violations. What's the most serious? The least?

Rosenbaum: I would say all the charges put together place Greitens in political jeopardy. The House released a report where the woman accused Greitens of sexual and physical abuse, charges that Greitens strenuously denies. But many lawmakers from both parties found the woman to be credible.

The campaign finance violations are difficult for Greitens, because he's already admitted to using the charity fundraising list for political purposes. His attorneys are trying to have another prosecutor besides Gardner try that case and are confident that he will be found not guilty eventually. But given that there may be a strong case on that front, it will likely provide more ammunition for lawmakers as they consider impeachment.

Cillizza: Finish this sentence: "By the end of the summer, the governor of Missouri will be _." Now, explain.

Rosenbaum: "By the end of the summer, the governor of Missouri will be doing all he possibly can to prevent being thrown out office."