The Justice Department has given Congress less than 15 percent of the texts between FBI officials Peter Strzok and Lisa Page – and that is all Congress is likely to get, at least until department experts finish an effort to recover an unknown number of previously lost texts that were sent and received during a key five-month period during the Trump-Russia investigation.

There is much confusion over some basic facts of the Strzok-Page texts. How many are there? How many relate to the two most politically-charged investigations in years, the Trump-Russia probe and the Hillary Clinton email investigation? How many have been turned over to Congress? And how many are left to be turned over to Congress?

The answers are complicated, but here is what I have been able to figure out from conversations with the Justice Department and Capitol Hill investigators.

The Justice Department has identified about 50,000 Strzok-Page texts. But that is apart from the texts between Dec. 14, 2016 and May 17, 2017 that were declared missing a week ago but are now being recovered. So, the total is apparently 50,000 plus the currently unknown number of formerly missing texts.

But that number refers only to the Strzok-Page texts that were sent and received on FBI-issued Samsung phones. There are a number of instances in the texts in which the two officials say that they should switch the conversation to iMessage, suggesting they continued to talk about FBI matters on personal Apple phones. For investigators, those are particularly intriguing texts – what was so sensitive that they couldn't discuss on their work phones? – but the number of those texts is unknown. And of course, they have not been turned over to Congress.

How many texts have been turned over? Both Justice Department and Capitol Hill sources say the total number is in the 7,000 range, which includes all the texts handed over on two separate occasions.

How many texts will be turned over? First, it's not possible to know how many texts from the Dec. 14, 2016 to May 17, 2017 time period will be recovered and turned over. But of the 50,000 the Justice Department already has in hand, officials say they have already turned over all they're going to give to Congress.

That means Justice has decided to allow Congress to see just 7,000 of a total of 50,000 Strzok-Page texts – slightly less than 15 percent of the total number of texts the Justice Department has now. Why is that? Justice Department officials point to a Jan. 19 letter from Assistant Attorney General Stephen Boyd to Capitol Hill investigators explaining which texts would and would not be turned over.

"The department is not providing text messages that were purely personal in nature," Boyd wrote. "Furthermore, the department has redacted from some work-related text messages portions that were purely personal. The department's aim in withholding purely personal text messages and redacting personal portions of work-related text messages was primarily to facilitate the committee's access to potentially relevant text messages without having to cull through large quantities of material unrelated to either the investigation of former Secretary of State Hillary Clinton's use of a personal email server or the investigation into Russian efforts to interfere with the 2016 presidential election."

Finally – and this could be significant or not – Boyd said that "in a few instances," the Justice Department consulted with the office of Trump-Russia special prosecutor Robert Mueller and made some redactions "related to the structure, operation, and substance of the [Special Counsel's Office]'s investigation because it is ongoing." Hill investigators don't really know what that covers. (The letter said if Congress has questions about redactions in a particular text, the department would "work with" Congress to further describe or reveal redacted information "in a closed setting.")

The bottom line is that the Justice Department has turned over a fairly small percentage of the Strzok-Page texts. Even assuming many of the texts would be personal – the two were having an extramarital affair, after all – some Hill investigators wonder whether roughly 43,000 of the 50,000 known texts were wholly personal.

And then, there is the question of those formerly missing texts. How many are there? How many will have something to do with Trump-Russia or Clinton emails? The time period involved, Dec. 14, 2016 to May 17, 2017, covered some of the key moments in the FBI's investigation of the Trump-Russia affair: conversations between Trump national security adviser Michael Flynn and Russian ambassador Sergey Kislyak; the completion and publication of the intelligence community assessment of Russian interference in the 2016 election; the briefing in which FBI director James Comey told President-elect Donald Trump about the Trump dossier; the president's inauguration; the nomination and confirmation of new Justice Department leadership; Flynn's interview with the FBI (conducted by Strzok); Comey's assurances to Trump that he, Trump, was not under investigation; a variety of revelations, mostly in the Washington Post and New York Times, about various Trump figures under investigation; Attorney General Jeff Sessions' recusal from the Russia probe; the firing of top Obama Justice Department holdover Sally Yates; Trump's tweet alleging he was wiretapped; Trump's firing of Comey; and, finally, the appointment of Mueller.

Right now, Justice Department officials are not saying how far along the process of recovering the texts is, or how long the work will take, or how many texts will ultimately be turned over to Congress. Just another unknown in a long and secretive investigation.

*Note: An earlier version of this story said there was a difference between Justice Department and Capitol Hill estimates of how many texts have been turned over. That was the result of a miscommunication, and now both sides agree the number is around 7,000.