Former Deputy Attorney General Rod Rosenstein as seen on November 27, 2018 in Washington, DC. Mark Wilson/Getty Images

Both sides have peppered Robert Mueller on why he did or didn't charge certain people with crimes during the course of his investigation. Republicans, for instance, want to know why he went after people like former Trump national security adviser Michael Flynn with obstruction of justice.

Rep. Jim Jordan: "What’s interesting, you can charge 13 Russians no one's ever heard of, no one’s ever seen. No one is ever going to hear of them. No one’s ever going to see them, you can charge them. You can charge all kinds of people who are around the president with false statements. But the guy who launches everything, the guy who puts this whole story in motion (Joseph Mifsud), you can't charge him. I think that's amazing."

A reminder: Mueller was not the one making the final call on who was charged or not. Deputy Attorney General Rod Rosenstein -- an appointee of President Trump -- was overseeing the investigation and had to sign off on what Mueller's prosecutors, who work for the Justice Department, did.

Rosenstein, of course, took over after AG Jeff Sessions recused himself, much to the dismay of President Trump.