Donald Trump asked whether he could push back against Justice Department efforts last year to recover any classified documents still in his possession during conversations with his lawyer over compliance with a federal subpoena, according to multiple sources familiar with notes taken by his lawyer and turned over to investigators.

Special counsel Jack Smith has obtained dozens of pages of notes that Trump's attorney Evan Corcoran took last spring, memorializing conversations with his client after the former president received the subpoena last May and before a key meeting with the Justice Department a few weeks later when Trump's legal team said they had turned over all classified records they could find, the sources told CNN.

The notes provide more insight into Trump's thinking and actions during a critical time frame as the special counsel pursues its criminal investigation into Trump's handling of classified material and the possibility he obstructed the investigation.

Some sources close to the former president say he was merely asking Corcoran for legal advice when he inquired about whether they could beat back the subpoena. But Trump has offered shifting explanations for why he did not return all the classified documents in a timely fashion. Trump has said he had "the absolute right" to take the documents as recently as this month at a CNN town hall.

Smith obtained the notes after an extraordinary court fight that ended with a federal judge ruling there was sufficient evidence to suggest Trump used his attorney in furtherance of a crime. That allowed prosecutors to pierce attorney-client privilege and obtain Corcoran's notes and additional grand jury testimony from him.

CNN reached out to a Trump spokesperson for comment. Corcoran's attorney and the special counsel's office declined to comment.

One source described Corcoran's notes as "overly detailed." Another source close to Trump's legal team said that some of them were surprised about the level of detail in Corcoran's notes. That source said multiple sets of notes were handed over to prosecutors and that they were significantly redacted to shield Corcoran's legal opinions in the notes from investigators.

Several sources said the notes reveal how Trump, when informed by his lawyer about the subpoena and how he should respond, asked if there was any way to fight it. Some contents of the notes were first reported by The Guardian.

The notes the DOJ has obtained reflect conversations between Corcoran and Trump after May 11 and through June 3, 2022, in which the attorney explained that the subpoena meant Trump would need to return all records marked classified to the government, sources said.

At that point, federal officials had spent months trying to recover classified and presidential records taken by Trump after he left the White House.

In response to the subpoena, Corcoran searched Trump's Mar-a-Lago estate in Florida for any classified documents. Corcoran told the Justice Department in June that he believed all White House records were in a storage room and nowhere else at the resort, and he said he gave all the records he found back to the federal government.

Sources said the notes indicate Trump aide Walt Nauta unlocked the storage room where documents were stored so that Corcoran could conduct his search. Nauta, who served as Trump's valet in the White House and now works as his body man, offered to help, but Corcoran declined, according to the notes, sources said.

CNN has reached out Nauta's attorney for comment.

Corcoran's notes don't explain how the FBI was able to find hundreds of additional classified records in its court-authorized search of the property, including in Trump's office at the resort in August 2022, according to one of the sources.

CNN previously reported that prosecutors have pressed for answers on why Nauta was seen on Mar-a-Lago surveillance footage moving boxes out of the storage room before and after the May subpoena, and that he had said in one interview with investigators it was at Trump's direction.

Trump's former attorney Tim Parlatore told CNN in an interview Saturday that he does not believe that Nauta did anything wrong but said Nauta may have given "inartful statements" to investigators.

"The fact that someone is moving boxes is not evidence of obstruction, it's evidence of an operating business ... because this is during the time period when he should be reviewing documents anyway to determine what is personal and what is presidential as part of the Presidential Records Act. There is nothing wrong with that," Parlatore said.

While Trump's legal team and Corcoran had fought efforts to force Corcoran to provide more evidence, a federal judge who reviewed the matter found that it was Trump -- not the attorney -- who may have committed a crime.

Corcoran had drafted a statement in June that attested Trump's team had done a "diligent search" of boxes moved from the White House to Florida and that all classified documents had been returned. Christina Bobb, the attorney who signed the letter, added the caveat, "to the best of my knowledge."