Here's what we've learned from the DOJ's photo of classified documents at Mar-a-Lago

The Justice Department's Tuesday night court filing in its ongoing investigation into classified documents stored at former President Donald Trump's Florida estate included previously unreleased details about the probe -- but perhaps none were as revealing as an FBI photograph of documents recovered from Trump's personal office during the bureau's August 8 raid.

Since the FBI's search of Mar-a-Lago, some members of Trump's team have downplayed the documents he kept at the resort as keepsakes that contained little sensitive information. But the photo released by Justice Department appears to refute those claims, showing document after document clearly labeled Secret and Top Secret.

In a court filing Wednesday evening, attorneys for Trump criticized the photo and its inclusion in the brief the government filed opposing Trump's request for a special master to review the retrieved documents.

"The Government’s Response gratuitously included a photograph of allegedly classified materials, pulled from a container and spread across the floor for dramatic effect," the filing said. "The Government pretends these are not historically important moments, telling this Court that not only does it object to a Special Master, but that the Movant should have no opportunity to challenge any aspect of this behavior and decision-making."

While portions of the FBI photo are redacted, a close review of the image reveals new clues about the kind of classified materials the former president was continuing to hang onto even after the Justice Department had issued a subpoena for their return.

Classified cover sheets

The photo shows numerous documents on the floor of Trump's personal office, including colored-coded cover sheets baring classification markings in big, bold lettering.

"An examination of these cover sheets alone tells you a lot," Douglas London, a 34-year CIA veteran, told ABC News regarding the DOJ photo. "As the most important intelligence customer, it should be no surprise that the president receives the most sensitive information -- and that's reflected in these documents."

The markings on the cover sheets include "TOP SECRET/SCI," which refers to Sensitive Compartmented Information classified as national intelligence "concerning or derived from intelligence sources," according to a separate document from the Director of National Intelligence reviewed by ABC News. This material may come from allies or informants, or from spying or eavesdropping.

A cover sheet near the bottom center of the photo also appears to show a "HCS-P/SI/TK" classification marking. HCS-P refers to HUMINT Control System, which is "designed to protect intelligence information derived from clandestine human sources, commonly referred to as "human intelligence." SI, or Special Intelligence, refers to a Sensitive Compartmented Information control system "designed to protect technical and intelligence information derived from the monitoring of foreign communications signals by other than the intended recipients," according to the FBI.

London, who is also the author of "The Recruiter: Spying and the Lost Art of American Intelligence," said, "If HCS is on the cover sheet, it means at least some of that information was drawn from human sources. And HCS-P is sensitive even by human source standards."

"Without being melodramatic, anything that helps an adversary identify a human source means life and death," he said. "People's lives are truly at stake."

There is also a handwritten marker next to the document that reads "2A," which appears to refer to "Item 2A" on the property receipt that was given to Trump's lawyers following the search. On the receipt, "Item 2A" is described as "Various classified/TS/SCI documents."

Dates on documents

Even though the contents of the documents can't been seen in the photo, the dates on some documents are visible. While it's not clear how or if the dates correlate to the classified information, they could provide potential clues regarding what Trump was publicly dealing with at the time.

Two documents with a "limited access" marker appear to be dated Aug. 26, 2018. While little else about those documents is visible, it's known that in August 2018, Trump was in the thick of special counsel Robert Mueller's investigation into contacts between the 2016 Trump campaign and Russia.

The day before Aug. 26, Trump, posting on Twitter, unloaded on Muller and then-attorney general Jeff Sessions, who had by then recused himself from the Russia probe, according to records maintained by The American Presidency Project by UC Santa Barbara.

One month prior to that, Mueller had indicted 12 Russian military intelligence officers for hacking and releasing Democratic emails during the 2016 campaign.

In addition, days before Aug. 26, 2018, Trump's former campaign manager, Paul Manafort, was found guilty on eight counts of tax fraud.

Aug. 26, 2018, was also the day after Sen. John McCain died.

A separate document shown in the photo bears the date May 9, 2018, which is the same day Trump gave a speech announcing he was withdrawing the United States from the 2015 Iran nuclear deal.

On that same day, Secretary of State Mike Pompeo met with North Korean leader Kim Jong Un in Pyongyang, which led to Trump announcing that Pompeo would be returning to the U.S. with three Americans who had been released from prison in North Korea.

"I'm very honored to have helped these great folks, but the true honor is going to be if we have a victory in getting rid of nuclear weapons," Trump said standing on the tarmac at Joint Base Andrews. "We have a meeting scheduled in a very short period of time. We have the location set. We'll see if we can do something that people did not think was going to happen for many, many years."

Trump ended up meeting with Kim the following month at a summit in Singapore, after which Trump announced that North Korea was no longer a nuclear threat to America. However North Korea resumed constructing new missiles the following month.