A week and a half has passed since the Internal Revenue Service first publicly admitted to singling out conservative groups. We know a great deal more about what happened than we did on May 10, but lots of unanswered questions remain.

Here's a rundown of what we know -- and what we still don't  -- about the ongoing story.

1) What happened?

What we know: In short, the IRS targeted certain conservative groups seeking tax-exempt status for extra scrutiny at beginning in 2010, according to an inspector general's report released last week. Lois G. Lerner, the agency official who oversees tax-exempt groups, first revealed publicly (in response to a question she planted) on May 10 that IRS personnel had targeted the groups. The IRS has insisted that the effort was a misguided attempt at greater efficiency rather than a partisan endeavor.

What we don't: The biggest question is what prompted the effort in the first place. The IG's report blacked out details in connection with the program’s start. The Cincinnati office, where the effort originated, will continue to be the subject of heavy scrutiny and more questions. Lawmakers will also continue to demand answers to questions about why it took so long to address the matter.

2) Who knew about it?

What we know: Details of the efforts reached the highest levels of the IRS in May 2012. Top White House aides learned about it in April of this year. White House counsel Kathryn Ruemmler informed senior White House officials including chief of staff Denis McDonough about the likely findings of the IG's report nearly a month ago, White House Press Secretary Jay Carney said Monday in an account that went well beyond what the White House had previously said. President Obama, the White House has said all along, did not learn of the targeting until the news media reported it on May 10, 2013, and did not learn about what the IG's report said until it was released last week. Deputy Treasury Secretary Neal S. Wolin learned about the IG's probe last year and Treasury Secretary Jack Lew testified that he first became aware of allegations that the IRS was targeting conservative groups on March 15, 2013. Some lawmakers knew about the IG probe in 2012.

What we don't: Who else at the White House aside from McDonough and members of the White House counsel's staff knew about the IG report. Meanwhile, lawmakers have also asked that outgoing acting IRS head Steven T. Miller disclose any communications with top administration officials about the matter. Republicans are charging that the actions are part of a culture of "intimidation" in the administration. The more people who were aware of the matter, and the higher up the ladder they were, the harder the GOP will press its case that this was more than an isolated effort by a few misguided individuals.

3) Did anybody break the law?

What we know: Authorities are looking into it. The Department of Justice has opened a criminal investigation into the matter. In addition, multiple congressional committees are holding hearings on the scandal, and the new acting director of the agency will conduct a 30-day review.

What we don't: Whether anyone actually broke any laws. Agency personnel may have run afoul of civil rights laws, the Hatch act, and they may have lied to Congress. Keyword being may. It's also possible that there were no legal violations, as Miller has insisted.

4) Who's out at the IRS?

What we know:  Miller resigned last week at the president's demand. Obama tapped budget official Daniel Werfel to replace him. Meanwhile, Joseph Grant, the commissioner of the agency’s tax exempt and government entities division, will retire early on June 3.

What we don't: Who's next. Lawmakers have called for Lerner to step down. And Sarah Hall Ingram, who was in charge of the tax-exempt organizations at the time conservative groups were targeted, now heads the agency's Affordable Care Act office. To be clear, Ingram has not been found of any wrongdoing so far, but she will likely continue to face scrutiny given her current position and GOP efforts to ding Obamacare by reminding the public about the IRS's role in implementing and enforcing the health care law.

5) What have the political consequences been for Obama?

What we know: So far, the president's job approval rating has sustained virtually no damage. A new Washington Post-ABC News poll shows Obama's approval rating has held steady. A CNN/ORC International survey conducted last week showed the same thing.

What we don't: How damaged Obama will be in the long term. What's clear from the Post-ABC poll is that 1) Most Americans think the IRS's decision was a deliberate effort to harass the groups, rather than a administrative mistake, and 2) Americans are split over whether or not the Obama administration is trying to cover up the facts. That not a good combination for the president. What's more, the IRS scandal could hardly have come at a worse time for the White House, which has also been dealing with mounting questions about last year's deadly attack in Benghazi, Libya and the Justice Department's decision to secretly obtain journalists' phone records as part of a leak probe. Things don't look so bad (politically) for the president right now, but that could change as all three stories unfold.