The special counsel, Robert S. Mueller III, in Washington last June. (Joshua Roberts/Reuters)

Friday’s indictment of 13 Russian nationals and three organizations answers some of the bigger outstanding legal and factual questions surrounding Russian interference with the 2016 presidential election. But a number remain unanswered, including the most obvious: Were Trump campaign officials involved, or Donald Trump himself? The indictment does not answer that question.

If the allegations in the indictment are true, it would certainly dispel any lingering doubts about whether Russians interfered with the election. The scope of the alleged efforts to tip the election toward Trump, and otherwise to meddle in U.S. politics — both before and after the election — is breathtaking. We may never know whether the outcome of the election was actually affected (contrary to what Trump claims, the indictment doesn’t answer that question either), but the charges provide a devastating account of the extent off Russian efforts

The indictment also resolves any debate over whether colluding to influence the election could be criminal. The president’s supporters have frequently claimed that, even if campaign officials did collude with Russians to impact the election, it would just be politics-as-usual, and not a crime.

But although there is no crime called collusion, in criminal law, working with others toward an unlawful end is known as conspiracy. And conspiracies to defraud the United States under 18 U.S.C. 371 include those that impair, obstruct, or impede lawful government functions such as carrying out a federal election. That is the legal theory that special counsel Robert S. Mueller III has used to charge the Russian defendants. Although this indictment charges only Russians with taking part in that conspiracy, the same charge would potentially apply to any American co-conspirators.

As mentioned earlier, the great unanswered question is whether the conspiracy included anyone involved in the Trump campaign. And the answer is: We still don’t know. The president’s supporters will point to language in the indictment about the defendants contacting “unwitting individuals” associated with the Trump campaign. Someone who is unwittingly involved is not a co-conspirator. If Mueller had the goods on members of the campaign, wouldn’t they be included in this indictment?

Perhaps — but not necessarily. There were reports late Friday afternoon that Mueller’s inquiry into Russian meddling is not yet complete. With a grand jury investigation shrouded in secrecy, any prediction is an exercise in reading tea leaves. But there could be any number of reasons for Mueller to not yet show his full hand.

Once an indictment is returned, the grand jury’s work on the charged offenses must cease. If the investigation is not yet complete, prosecutors could choose to bring an initial indictment against Russian participants while continuing the grand jury investigation against others.

That procedure could make sense. Friday’s indictment sets a dramatic stage for anything that will follow. It provides the most detailed public account to date of the activities that Mueller is charged with investigating, and puts to rest any notion that there is “no there there.” It also lets other potential targets know that Mueller’s knowledge of Russian interference is extensive, and that the wisest course may be to cooperate rather than to try to obfuscate or obstruct.

Bringing the first major indictment against only Russian individuals is also a brilliant rebuttal to those who argue (without basis ) that Mueller’s inquiry may be politically motivated. It allows Mueller to reveal the breadth and seriousness of the misconduct without any distracting political sideshows. Surely the condemnation of the conduct set forth in Friday’s indictment will be bipartisan and overwhelming. That will give Mueller’s investigation considerable momentum and should provide substantial political insurance against any potential moves to fire the special counsel.

If the investigation into election meddling remains ongoing, then a superseding indictment could later add additional co-conspirators and charges. On that point, it is interesting to note the indictment’s allegation that the defendants conspired not only with each other , but also with “others known and unknown to the Grand Jury.” This could just be boilerplate language — or it could be a signal about things to come.

Finally, the other unanswered questions surrounding Mueller’s inquiry relate to other criminal areas such as obstruction of justice. There have been clear signs that Mueller may be probing potential efforts to thwart the Russia investigation and/or efforts by campaign officials to conceal Russian contacts. That parallel area of inquiry is not affected by this indictment. The obstruction of justice-related shoes, if any, still remain to drop.

The indictment alleges an astonishing conspiracy. It remains to be seen just how widespread the conspiracy was, and whether there were criminal efforts to cover it up. Mueller may be just getting started.