The Federal Bureau of Investigation revealed Thursday that it had failed to turn over hundreds of documents, amounting to 3,100 pages of investigation reports, photographs, written correspondence and tapes relating to the case against Timothy McVeigh, the admitted Oklahoma City bomber.

The Justice Department decided Friday to stay McVeigh's execution since the materials should have been handed over to McVeigh's attorneys before his trial.

DOJ special attorney Sean Connelly wrote to McVeigh's attorneys Wednesday that additional documents relating to the Oklahoma City bombing case came from reviews of 26 databases and included a number of "302's," or reports filed by agents named for the number on the form with which they must be submitted. They also include "inserts" filed by field agents, along with everything from photographs and correspondence to audio and video tapes.

Sources told Fox News Friday that many of the forms pertain to "John Doe No. 2," a suspect who was described by witnesses but never identified. The information may also be crucial to the defense of Terry Nichols, a convicted co-conspirator who has always maintained others, not him, were involved.

The documents were uncovered during a routine evidence-gathering conducted by agent Danny Defenbaugh, who was in charge of the Oklahoma City bombing investigation.

The FBI said it wants to make clear that the documents, part of millions of pages of evidence in the case, were not withheld intentionally, but were mistakenly left out during the discovery process.

The letter accompanying the documents written by Connelly read, "We do not believe anything being produced is material bearing on the federal convictions or sentences of Timothy McVeigh or Terry Nichols."

Connelly's letter said the discovery of additional materials came "after an FBI archivist requested that all OKBOMB-related materials be sent to the Oklahoma City field office for archiving."

He also wrote that "FBI Director Louis J. Freeh and the agent in charge of the bombing probe had requested on numerous occasions prior to trial that each field division and legal attache forward all OKBOMB-related materials to the Oklahoma City division, and had received assurances that all such materials had been forwarded."

Two government sources told The Washington Post that some of the material was duplicated information previously given to the defense, but another federal source said most of the material had not been seen by the defense.

Connelly wrote that none of the materials makes any "showing of either man's actual innocence."

Sharon Kehnemui is a digital marketing consultant and founder of Frequency Partners. She is a former senior politics editor for FoxNews.com. Follow her on Twitter @digisharon.