An early draft of former FBI Director James Comey's statement closing out the Hillary Clinton email case accused the former secretary of State of having been "grossly negligent" in handling classified information, newly reported memos to Congress show.

The tough language was changed to the much softer accusation that Clinton had been "extremely careless" in her handling of classified information when Comey announced in July 2016 there would be no charges against her.

The change is significant, since federal law states that gross negligence in handling the nation's intelligence can be punished criminally with prison time or fines.

Spokesmen for the FBI and Clinton did not immediately return phone calls or emails seeking comment.

The draft, written weeks before the announcement of no charges, was described by multiple sources who saw the document both before and after it was sent to the Senate Judiciary Committee this past weekend.

"There is evidence to support a conclusion that Secretary Clinton, and others, used the email server in a manner that was grossly negligent with respect to the handling of classified information," reads the statement, one of Comey's earliest drafts from May 2, 2016.

The sources who had seen the early draft, who spoke on condition of anonymity because they were not authorized to speak to the media, said the draft statement was subsequently changed in red-line edits on or around June 10 to conclude that the handling of 110 emails containing classified information that were transmitted by Clinton and her aides over her insecure personal email server was "extremely careless."

The documents turned over to Congress do not indicate who recommended the key wording changes, the sources said.

Memos show that at least three top FBI officials were involved in helping Comey fashion and edit the statement, including Deputy Director Andrew McCabe, General Counsel James Baker and chief of staff Jim Rybicki.

The Senate Judiciary Committee on Monday evening sent a letter to current FBI Director Christopher Wray demanding the FBI identify who made the changes and why.

"Apparently, as of May 2016, then-Director Comey and other FBI officials believed the facts fit that gross negligence standard until later edits were made," Chairman Chuck Grassley (R-Iowa) wrote to Wray in the letter demanding more information.

While Comey told Congress last year that he would never have prosecuted Clinton without proof she intended to violate a law, the editing of his statement suggests there might have been dissent within the FBI about that decision.

Sources who had seen the draft said they are certain to renew interest among congressional Republicans into Comey's decisionmaking.

"The red-line history clearly shows the original statement was designed to allege Clinton committed gross negligence and then someone changed it to extreme carelessness," one source said. "Clearly there was a difference of opinion on the term derived right from the statute."

When Comey announced the decision to not bring charges against Clinton in July 2016 - shortly after Clinton had secured the Democratic nomination to run for president against Donald Trump - he said agents decided not to pursue criminal charges under the statute because they could not prove she intended to violate laws like the Espionage Act.

But he harshly criticized Clinton for setting up a personal email server outside the State Department's security apparatus and then using it to transmit classified information.

"Although we did not find clear evidence that Secretary Clinton or her colleagues intended to violate laws governing the handling of the classified information, there is evidence that they were extremely careless in their handling of very sensitive, highly classified information," Comey said at the time.

"There is evidence to support a conclusion that any reasonable person in Secretary Clinton's position or in the position of those with whom she was corresponding about the matters should have known that an unclassified system was no place for that conversation," he said.

Comey's decision to not to seek criminal charges has been controversial since it was announced, with politicians and legal scholars alike debating whether intent was necessary to pursue criminal charges.

Section 793 of federal law states, "Whoever, being entrusted with or having lawful possession or control of any document, writing, code book, signal book, sketch, photograph, photographic negative, blueprint, plan, map, model, instrument, appliance, note, or information, relating to the national defense, (1) through gross negligence permits the same to be removed from its proper place of custody or delivered to anyone in violation of his trust, or to be lost, stolen, abstracted, or destroyed, or (2) having knowledge that the same has been illegally removed from its proper place of custody or delivered to anyone in violation of its trust, or lost, or stolen, abstracted, or destroyed, and fails to make prompt report of such loss, theft, abstraction, or destruction to his superior officer - shall be fined under this title or imprisoned not more than ten years, or both."

Some legal scholars have argued Comey's analysis of the law was correct, citing a 1941 Supreme Court ruling saying the gross negligence statute was not constitutionally vague as long as prosecutors showed there was "intent or reason to believe that the information to be obtained is to be used to the injury of the United States."

But other scholars noted that prosecutions have been brought since the 1941 case in the military courts where intent wasn't required.

Comey argued in testimony before Congress that while he was aware of the gross negligence statute, he did not believe any federal prosecutor would pursue that standard.

"I know the Department of Justice, I know no reasonable prosecutor would bring this case. I know a lot of my former friends are out there saying they would. I wonder where they were in the last 40 years, because I'd like to see the cases they brought on gross negligence. Nobody would, nobody did," he said.

But Comey also conceded in public statements that the FBI also found some evidence of criminality during the email probe.

"Although there is evidence of potential violations of the statutes regarding the handling of classified information, our judgment is that no reasonable prosecutor would bring such a case," he explained.