We don't know exactly what Tamerlan Tsarnaev did during his visit to Russia in 2012. We do know that the Federal Bureau of Investigation has told us very little about its inquiry at that time into the man now accused of bombing the Boston Marathon.

No, I'm not expecting the FBI to divulge specifics that would in any way compromise its investigation -- some things will have to wait until charges are filed and the national security threat has passed. But the FBI initially bungled its disclosure of the inquiry, first telling the news media on Friday that it had no record on either Tamerlan or his brother, Dzhokar, then quickly retracting and explaining that a foreign intelligence agency had asked it to investigate the older Tsarnaev. As we saw in the aftermath of the Sept. 11, 2012, attack on a U.S. diplomatic compound in Benghazi, Libya, botched communications from the government quickly become fodder for political grandstanding and conspiracy theories.

The FBI took a big risk last week in releasing photos of the suspects, and that crowdsourcing of the investigation paid off in a quick apprehension. It should build on that spirit of engaging the public by answering as many of these questions as it thinks can safely be discussed at this early stage. Sharing information with a public eager for more knowledge of what led to the murderous act could calm national security fears and nip in the bud accusations that the government is looking to hide something.

1. Was it Russia that requested the agency investigate Tsarnaev?

2. What specific information was shared about Tsarnaev by the government that put in the request?

3. Was this business as usual? In other words, how many such requests does the bureau receive each year and how many lead to investigations? Assuming it was Russia that asked about Tsarnaev, how often does Moscow ask for investigations, and how many times have its suspicions been founded?

4. When did the bureau speak to Tsarnaev and other family members? Did it speak to or investigate his younger brother, Dzhokar?

5. What was the scope of the investigation -- did it begin and end with a standard records check and interview of family members? How many agents were involved, and how long did it take? How did it compare with investigations after similar requests?

6. Did anyone seek permission under the Foreign Intelligence Surveillance Act to monitor Tsarnaev's communications?

7. On what grounds was the investigation dropped? Was the agency convinced Tsarnaev posed no threat, or did it simply think it had performed due diligence and moved on?

8. Representative Mike Rogers, a Michigan Republican and former FBI agent, said that when the bureau asked the foreign intelligence service for more information, it received no cooperation. What did the bureau ask for and what was the foreign nation's specific reply?

9. Was Tsarnaev placed on any Transportation Security Administration list, and were any other national-security agencies informed that he had been investigated?

10. Why did the FBI initially say it had no records on the Tsarnaevs, and what caused it to retract that statement?

(Tobin Harshaw writes editorials on national security for Bloomberg View. Follow him on Twitter.)