More than 18,000 such forms were generated by investigators during the Oklahoma City investigation. It is possible some of the recently discovered forms are duplicates.
None of the new material is considered favorable to McVeigh, but to withhold evidence either by design or by accident is a serious matter and potentially could lead to a hearing that would delay the execution.
In most cases, a disclosure that evidence was withheld would make a motion for a new trial almost certain.
At a minimum, that would involve a hearing that would delay the death sentence.
But that is up to McVeigh and his attorneys. McVeigh has said he wants to die. It is not known what he has conveyed to his attorneys, and he might tell his defense team not to interfere.
Oklahoma City survivors, meanwhile, were stunned by the late development.
"It'll set everybody back several steps," said survivor Glenda Riley. "I really think it'll set everybody back."
McVeigh is scheduled to die by lethal injection at the federal prison in Terre Haute, Ind., at 7 a.m. CST on May 16. His execution would be the first federal death penalty administered since 1963. It will broadcast on closed circuit television so survivors and families of those killed can watch.