The court's decision Monday to order a response from the Justice Department raised the possibility that the justices would hear the case involving Nichols, convicted as a conspirator in the April 1995 bombing of the Alfred P. Murrah Federal Building.
This came in the wake of disclosure that the FBI failed to provide McVeigh's attorneys with thousands of documents at the time of McVeigh's trial in 1997.
Lawyers for McVeigh last week asked a federal court in Denver to stay his scheduled June 11 execution for the bombing at a federal prison facility in Terre Haute, Ind.
But that order did not address allegations by Nichols' lawyer that the FBI may have deliberately withheld information both from the bombing defendants and from federal prosecutors.
U.S. District Judge Richard Matsch, who presided over the Nichols and McVeigh trials, has set a June 6 hearing to consider whether to grant McVeigh a stay of execution on his claims the government committed a "fraud upon the court" by withholding more than 4,400 pages of documents.
Nichols' lawyers want the high court to reconsider its denial on April 16 of his appeal claiming the government withheld information that could have helped his defense at trial and sentencing.
The lawyers want the Supreme Court to grant his request and direct a U.S. appeals court to send the case back to Matsch for further proceedings on how the documents would affect Nichols and to make sure all withheld materials have been produced.
Even before the discovery of the documents, Nichols had been seeking at least an evidentiary hearing before Matsch on his claims that helpful information had been withheld.
McVeigh, 33, is being held in a special death-row unit at a federal prison in Terre Haute, Indiana as he awaits Match's ruling on whether the execution will go forward on schedule.
Nichols, a former U.S. Army buddy of McVeigh, is serving a sentence of life in prison. He was convicted of conspiracy and involuntary manslaughter for the deaths of eight federal agents in the building when the bomb went off.
Nichols also is awaiting trial in Oklahoma on separate state murder charges that carry the death penalty.
The court routinely denies nearly every request for a second chance made by losing parties. It is quite unusual for the court to ask for a response to such a request but is still far from an indication that the court will grant Nichols' appeal.
The court denies the overwhelming majority of rehearing petitions, even after requesting a response.
Attorney General John Ashcroft delayed McVeigh's execution until June 11 to give defense lawyers time to look over the new material but said nothing in it would undermine McVeigh's conviction or death sentence.
McVeigh has since asked for another postponement, and he could ultimately follow Nichols' lead and seek a new trial or sentencing hearing.
Ashcroft said he will fight any attempt to delay the execution beyond June 11.
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