The controversy over special counsel Robert Hur’s characterization of President Joe Biden’s memory has obscured one of the most surprising findings in his report: evidence that Biden knowingly kept classified materials at home for years and failed to turn them in.

After a yearlong investigation, Hur found that the evidence of “willful retention” — the language in the criminal statute — wasn’t strong enough to justify a prosecution. And he explained in detail why the criminal charges against former President Donald Trump for his handling of classified materials include far more serious allegations of misconduct than Biden’s case.

To Democrats, Hur’s finding that there was no criminal case to bring against the president is the most important takeaway.

But to some national security experts, the disclosure that Biden told his ghostwriter that he discovered classified documents in his Virginia home in 2017 — with no indication he returned them — was unexpected and troubling. So was the revelation that Biden disclosed classified information to the ghostwriter on at least three occasions, and that he stored notebooks full of state secrets in unlocked drawers in his home office.

They said a senior government official like Biden should be held to a higher ethical standard than whether a jury would convict him of a felony.

“It may not be criminal, but it’s reckless and awful, because you have no idea what sources and methods you are putting at risk,” said NBC News legal contributor and former federal prosecutor Chuck Rosenberg. “Someone who served as the vice president of the United States should know better.”

White House spokesperson Ian Sams said the Hur report “found the totality of evidence in fact does not support willful retention.”

“The report also notes how, in early 2017, the President did find another marked classified document and did turn it in, via his aide, which illustrates precisely what he told the special counsel,” Sams said. “That if he had found classified documents he would have returned them.”

Sams also noted that the Hur report says prosecutors could not establish that Biden knew information was classified when he shared it with his ghostwriter.

Biden, who has been immersed in the world of state secrets for decades, has taken a firm line on the handling of classified documents. When asked in September 2022 about Trump’s storing of classified documents at his home in Mar-a-Lago, he replied, “How could that happen? How could anyone be so irresponsible?”

And when classified documents were discovered in his Delaware garage and other places in December 2022, he said he was surprised, adding, “People know I take classified documents and classified information seriously.”

But Hur’s report says the documents found in a box in Biden’s garage, many with classification markings, mainly relate to his role in opposing a 2009 Obama administration troop surge in Afghanistan. Some were classified “top secret.” When they were discovered in late 2022, Biden’s team immediately called the FBI.

The special counsel said the evidence suggests these were the same documents that Biden was referring to in 2017, when he told a ghostwriter in a recorded interview that he had “just found all the classified stuff downstairs,” in a Virginia home he rented after leaving the vice presidency. The special counsel found no evidence that any classified documents were turned in at that time.

That is perhaps the report’s most damaging finding: Biden knew he had classified documents in 2017, but there is no evidence he took steps to turn them in.

But the report says the special counsel was unable to conclusively identify those documents, and therefore prosecutors could not prove to a jury exactly what that 2017 comment referred to.

Still, the report contradicted the message that the White House had voiced for months: that Biden didn’t know he had classified documents in his home and office.

Sams, the White House spokesman, said Biden told the special counsel that he believed he was referring to a handwritten letter he had sent President Barack Obama, a letter that was not marked classified.

But the Hur report says Biden “did not remember anything at all about this incident” — an especially important factor that Justice Department officials say prompted Hur to include the controversial assessments of Biden’s mental state, including that he would appear to a jury as “a sympathetic, well-meaning, elderly man with a poor memory.”

The ghostwriter, Mark Zwonitzer, was helping Biden write a memoir about his son’s death called “Promise Me, Dad.”

The report says Biden also shared with Zwonitzer classified information on three occasions from notebooks Biden had compiled during his time in office. Biden then stored those notebooks in insecure locations, it says.

The report also says “the evidence shows convincingly” that Biden knew the notebooks contained classified information. But it also acknowledges that prosecutors would not be able to prove to a jury that the exact passages Biden read to the ghostwriter were classified.

The report notes that other presidents, including Ronald Reagan, took home notebooks or diaries containing classified information and were never prosecuted. And it says Biden believed he had a right to keep his own notebooks. So, it concludes, a prosecution would be difficult.

Still, there were warning signs. The Hur report found that in October 2016, as then-Vice President Biden was gathering notecards to use in writing his memoir, a military aide working in his office raised concerns that the notes contained classified material. The aide’s immediate supervisor disagreed, so she wrote an email for the record saying she believed “these records are being mishandled.”

In another instance, the report says, a lawyer working for the vice president’s office noticed that some of the notecards he was collecting “contained notes about the President’s Daily Brief,” which often contains some of the most sensitive intelligence the U.S. government collects.

Attorney Mark Zaid, who specializes in cases involving classified information, said Hur’s findings were “worse than I expected by way of the president’s conduct over the years. But even then, none of it surprised me.”

“His conduct was emblematic of what we see with former senior government officials all the time,” Zaid added. “It sends a horrible message to the workforce that our senior leadership is not held to account for its mishandling of classified information.”

Zaid said a typical client who did what Biden had done probably wouldn’t be prosecuted, but “they would have faced loss of federal employment and/or their security clearance without a doubt.”