The congressional investigations could end up answering some of the most intriguing questions of the Trump controversies.

While special counsel Robert Mueller continues his own probe into possible collusion between the Trump campaign and the Russian government, the Democrats are hoping to shed more light on areas that so far have been left in the shadows.

Democrats are taking over the House on Thursday, with plans to investigate President Trump and his administration on a number of fronts .

Here are three of those questions:

Donald Trump Jr. Carolyn Kater/Associated Press

Which mystery person did Donald Trump Jr. call before the Trump Tower meeting?

Adam Schiff, the incoming chairman of the House Ways and Means Committee, said he wants to know who Donald Trump Jr. called before the pre-election meeting he had at Trump Tower with Russians who were promising dirt on Democrat Hillary Clinton.


While setting up the meeting, Trump Jr. called a blocked cellphone number. Some wonder if he was looping in his father. The Republicans who previously controlled the committee did not seek the number.

“One key question, of course, is: What was the president’s role in that meeting in Trump Tower?” Schiff told The New York Times. “That phone call may lead to a place the Republicans didn’t want to go and so they were unwilling to get the answer.” Schiff, however, said it would be “very simple to find out and we do intend to find out” who was behind the blocked number.

What prompted Kremlin agent Maria Butina to ask Trump in July 2015 a question about US sanctions on Russia?

“I believe I would get along very nicely with [Russian President Vladimir] Putin, OK?” Trump told Butina from the podium at a Las Vegas event. “I don’t think you’d need the sanctions. I think that we would get along very, very well.”

Schiff said on MSNBC it would be fascinating to learn more from Butina, who has been convicted and is cooperating with federal prosecutors.


Maria Butina’s booking photo. Alexandria Sherif’s Office/AFP/Getty Images

“That question that she asks [Trump] that he uses as the opportunity to express his opposition to Russian sanctions — was that a prearranged question? And if so, then who was doing the prearranging?” Schiff said.

Some of Trump’s own advisers reportedly found the question coming from the audience at the event strange.

“[Special counsel] Bob Mueller may know some of the answers to some of these questions. It’s our intention, the Intel Committee, to find out and do what we said we would in the beginning, which is follow the evidence wherever it may lead,” Schiff said.

Donald Trump Chip Somodevilla/Getty Images

What is in Trump’s tax returns, and why is he adamant about not releasing them?

It is a central mystery of Trump’s presidency. Trump has steadfastly refused to release his tax returns, breaking with a tradition that goes back decades.

What story could the returns tell?

Will they reveal he has financial ties to Russia and other countries that he has been dealing with as president on the world stage? Will they show his income and charitable contributions were lower than people thought? Will they provide clues leading investigators down other paths?

Incoming House Ways and Means Chairman Richard Neal of Massachusetts said shortly after the midterm elections that Democrats would seek Trump’s tax returns.

Politico reported this week that Neal will take a go-slow approach, hoping to build a case with the public for the release before seeking the records. Trump lawyer Rudy Giuliani told CNN the president would fight in court against releasing the returns.