After the election, Trump publicly mocked the Central Intelligence Agency for its reports on Russian hacking, named his Russian-paid adviser to head the National Security Council, and is now publicly considering for secretary of state one of the most Putin-friendly businessmen in the western world.

Do Americans really need secret information from the CIA to discern the pattern here?

Yet important questions about the Russian manipulation of U.S. politics do remain unsettled. Four U.S. senators, including former Republican presidential nominee John McCain, have now called for an inquiry into Russia’s actions to aid Donald Trump. The incoming Trump administration opposes such an inquiry, perhaps for the compelling reason that it knows how embarrassing it might be. The immediate question is whether the Republican majority in the Senate will proceed over the objection of a Republican president. Let’s hope it does. If it does, here are some things to which it would be helpful to learn answers:

Exactly which institutions did the Russians hack?

There is a partial list, including the RNC, the DNC, the DCCC, and the personal email of Center for American Progress chair John Podesta. But a full list would reveal the scale and pattern of Russian intentions. It has suddenly become intensely controversial whether the Russians did indeed hack the Republican National Committee (as asserted by the CIA and by the chairman of the House Homeland Security Committee) or not (as passionately denied by Reince Priebus, the RNC chair who will serve as chief of staff in the Trump White House). A lot turns on that uncertainty. If Russian espionage hacked the RNC—but chose not to leak RNC emails—that would say a lot about Russian intentions. It would also indicate who in American public life might now be vulnerable to future Russian blackmail. If Priebus is correct, and the CIA is wrong, that the Russians did not hack the RNC, that too raises important questions: Was RNC security more robust than DNC security? Or did the Russians not try the RNC? If not, why not?

When did the hacks occur?

In particular, did the pace of Russian hacking accelerate as Donald Trump neared the Republican nomination? This would be important to know both in its own right, but also because it might shed light on the ominous question that follows.

Was there coordination?

Was information shared in any way, or did anyone directly or indirectly connected to the Trump campaign offer any advice to any foreign entity about where and how to hack—beyond the president-elect’s own public encouragement? What compromising information might Russia have upon persons connected to the Trump campaign—including of course the president-elect himself?

Are there financial ties?

The Senate inquiry should also subpoena any Trump organization business records that might shed light on any debt or obligation that the Trump family might have in Russia and any significant income flows from Russia. Beyond the obvious political ties Trump has to Putin, do Russian interests have any hold upon him and his family—financial or otherwise?