WASHINGTON (AP) — Special counsel Robert Mueller’s team of investigators is in possession of a letter drafted by President Donald Trump and an aide, but never sent, that lays out a rationale for firing FBI Director James Comey, according to a person familiar with the investigation.

The letter was written in the days before the May 9 firing of Comey, but was held after objections from the president’s lawyer and others, according to two other people familiar with the process who were not authorized to discuss it publicly and spoke on condition of anonymity.

On that day, the White House released a different letter announcing Comey’s firing, one signed by Deputy Attorney General Attorney Rod Rosenstein that cited the handling of the Hillary Clinton email investigation as a basis for Comey’s dismissal.

Trump had been fuming about Comey for weeks, upset that he would not say publicly that the president was not under investigation, which Trump said Comey had assured him privately.

That was in the earlier letter and was part of the president’s rationale for firing Comey. It was later excised — only to be partially restored in the final letter at Trump’s behest.

The earlier letter could serve as key evidence to Mueller’s team, which is now investigating whether Trump fired Comey to impede the FBI investigation into his campaign associates’ ties to Russia. The White House has said Trump was acting on the Justice Department’s recommendation when he fired Comey, though the president said in a television interview days later that he was thinking of “the Russia thing” when he made the move and had planned to fire “regardless of recommendation.”

The new letter, which was first reported by The New York Times, could provide additional context on Trump’s thinking and motive as he prepared to oust Comey.

The Justice Department turned the letter over to Mueller’s team, according to a person who was not authorized to publicly discuss the situation and spoke on condition of anonymity. A statement from the Justice Department said the department had been fully cooperative with Mueller’s investigation and would continue to do so.

One week after Comey was fired, Rosenstein appointed Mueller as special counsel to oversee an investigation into potential coordination between the Trump campaign and Russia. That investigation, which had been overseen by Comey, is also looking into the financial dealings of several Trump associates.

During a May weekend at the president’s New Jersey golf club, Trump asked White House aide Stephen Miller to draft a letter outlining a case for Comey’s firing, according to two people familiar with the situation. But the letter, which contained a rationale for the dismissal, was not sent after White House counsel Don McGahn objected, thinking some of its contents were problematic, according to one of the people familiar with the letter.

The Associated Press has not reviewed the letter.

Rosenstein, in a statement to Congress, has said that he learned on May 8 of Trump’s plans to fire Comey, and that he agreed with the decision. He has said that in one of his first conversations with Attorney General Jeff Sessions, they discussed the need for new leadership at the FBI.

He wrote a memo to Sessions summarizing his concerns about the FBI director’s performance and said he finalized it the next day and presented it to Sessions. He said he did not intend for his memo to be a “statement of reasons to justify a for-cause termination,” and that it was “not a survey of FBI morale or performance.”

Miller, the firebrand aide who helped design Trump’s travel ban and hardline immigration policies, had become a trusted adviser to the president during the campaign and remained in his inner circle even after fellow nationalist and chief strategist Steve Bannon began to fall from the president’s favor.

Instead of using the directive Miller penned, a separate letter written by Rosenstein and focused on Comey’s handling of the investigation into Hillary Clinton’s private email server was sent to the FBI director when he was dismissed.

By JONATHAN LEMIRE and ERIC TUCKER