Washington, Feb 9 (IANS): A special counsel investigating US President Joe Biden's handling of classified documents from his vice-presidency in 2017 has decided not to prosecute him but raised serious questions about his mental condition because of his age, which has become an issue as he seeks a second term that will further cement his place in history as the oldest American President.

Robert K. Hur, the special counsel, said in the report submitted to US Attorney General Merrick Garland on Thursday, "no criminal charges are warranted" in the case but the investigation found that President Biden had "willfully retained and disclosed classified materials after his vice-presidency when he was a private citizen".

Biden had shared the papers with the ghost writer of his memoir "Promise Me, Dad".

The documents pertained to foreign policy issues on Afghanistan and notebooks that contained nothing from briefings on national security and foreign policy.

The counsel, however, handed a severe indictment of Biden's mental acuity.

"We have also considered that, at trial, Biden would likely present himself to a jury, as he did during our interview of him, as a sympathetic, well-meaning, elderly man with a poor memory."

He further said: "Based on our direct interactions with and observations of him, he is someone for whom many jurors will want to identify reasonable doubt. It would be difficult to convince a jury that they should convict him by then a former President well into his 80's of a serious felony that requires a mental state of willfulness."

The case against Biden came up in the aftermath of the loads of classified documents that were discovered to have been carried away by former President Donald Trump when he left office in January 2021.

He had refused to hand them back to the government and he has since defended his actions claiming these were not classified papers because, in exercising his presidential powers, he had declassified them.

Biden's age and his mental acuity are facing continued scrutiny, even within his own party. He is 81, and if re-elected, he will be 82 at the time of second inauguration. He is already the oldest President in US history. He has publicly struggled with memory. He recently mixed up French President Emmanuel Macron with one of his predecessors, Francois Mitterrand and Germany's former Chancellor Angela Merkel with her predecessor Helmut Kohl.

Trump, who is no spring chicken at 77 and will probably be the Republican candidate to take on Biden in November, has had his own challenges. He had mistaken Nikki Haley, the former ambassador to UN who is the remaining rival in the field for the Republican nomination, for Nancy Pelosi, the former Democratic Speaker of the House of Representatives who had green-lit two impeachments of Trump, making him the only President to be impeached twice.