The U.S. Supreme Court lifted a stay of execution for Steven H. Oken last night, clearing the way for the condemned Maryland inmate to be put to death by midnight tomorrow -- nearly 17 years after he brutally assaulted and killed a Baltimore County college student and newlywed.

The justices reversed a federal appellate court that only hours earlier had sided with Oken and upheld the stay. At issue was whether the triple murderer was denied due process when prison officials delayed providing his attorneys the lethal injection protocol.

That appellate decision pushed the state of Maryland, under acute time pressure in its effort to execute Oken before his death warrant expires tomorrow, to turn to the only other legal forum available. The attorney general's office asked Chief Justice William H. Rehnquist for an immediate reversal by the Supreme Court. By 3 p.m., briefs in what could be the final round in the case were before the justices.

Shortly before 8 p.m., they acted. Not only did the high court vacate the stay, it also denied Oken's claim that the way Maryland performs lethal injection is unconstitutional. No explanation was provided, only a three-line paragraph. Individual votes were not detailed, though Justices John Paul Stevens, Ruth Bader Ginsburg and Stephen G. Breyer went on the record as supporting Oken on both issues.

The sudden shift from victory to defeat caught defense attorney Fred Bennett by surprise.

"This is not good," he said. Although he intends to return to two federal courts this morning to push a claim that Oken received ineffective counsel at his sentencing in 1991, the chance of its success may be as remote as Oken's request that Gov. Robert L. Ehrlich Jr. (R) commute his sentence to life without parole.

A spokesman for the governor, a death penalty supporter, said Ehrlich would make no decision on clemency last night. Bennett said he would try to meet with Ehrlich or his legal counsel today.

"Mr. Oken is aware. He understands the situation," said Bennett, who has been involved in the case for more than a decade. "And I believe he is ready, so to speak, to meet his maker."

The attorney general's office assured Bennett that Oken would not be put to death before the defense can pursue its options this morning, Bennett said. But it is likely that corrections officials will not wait more than a day before they move the inmate from the Supermax prison in downtown Baltimore across the street to the execution chamber. State law prohibits officials from publicly disclosing the planned time and date of death in advance.

Maryland Solicitor General Gary Bair said the Supreme Court ruling "effectively ends the litigation." Unless the defense can persuade a federal judge to intervene regarding Oken's purported ineffective representation at trial, his fate is sealed.

The family of his first victim, Dawn Marie Garvin, having twice before watched courts grant Oken reprieves, reacted with "a great sense of relief, " said Garvin's father, Fred Romano. A Baltimore County prosecutor reached Romano on his cell phone as he, his son and half a dozen friends demonstrated outside the prison last night. She told him of the Supreme Court's action and its import: "The execution is on. That's all the details she gave me, and she said congratulations," Romano recounted.

It was Romano who discovered his daughter's body in her White Marsh apartment that November night in 1987. She had been sexually violated, brutally so, and then shot in the head. Two weeks later, Oken sexually assaulted and killed his sister-in-law, Patricia Hirt, before fleeing to Maine, where he then did the same thing to a young motel clerk named Lori Ward.

Oken, now 42, received his capital sentence for Garvin's death, the details of which his own attorney described yesterday as "terrible circumstances."

Garvin's husband, who will be a witness at Oken's execution, was nearly at a loss for words by evening. "It's almost here, a step closer," Keith Garvin said from his home in northeastern Maryland. "We just said, 'This one's for Dawn.' "

At an early afternoon news conference, defense attorneys emphasized Oken's constitutional right to question the manner and method by which he will lose his life. The defense no longer contested the Baltimore County man's capital sentence, only the specifics of how it will be carried out. Bennett argued that Maryland's last execution in 1998 was botched by ill-trained prison staff -- the state acknowledged in court Monday that an intravenous line leaked during the procedure -- and said he feared a repeat would subject Oken to extreme suffering.

"Any defendant that faces death by lethal injection has the right to raise an Eighth Amendment claim," Bennett said.

The U.S. Court of Appeals for the 4th Circuit, the conservative court in Richmond that denies most death row appeals, granted Oken relief by a 2 to 1 vote that maintained the execution stay that U.S. District Judge Peter J. Messitte ordered Tuesday. Over the years, Oken's case had gone before the 4th Circuit several times; yesterday marked the first time the judges gave him what he wanted.

In its emergency application to Rehnquist, Maryland said Messitte never should have granted the prisoner's "last-minute legal plea." It urged the Supreme Court to distinguish the case from one the justices decided unanimously three weeks ago, in which they allowed an Alabama death row inmate a late challenge to a surgical technique that his executioners told him -- with little notice -- they would use to prepare him for lethal injection.

In that opinion, the justices said David Nelson should be given a hearing. Still, they stressed that their finding was "extremely limited" and should not "open the floodgates to all manner of method-of-execution challenges."

The Maryland attorney general's brief reminded the justices of their wording. It said Oken has known for years that he could die by injection, as well as the basic steps the state follows.

"Oken insists even now the information he has been given does not suffice to ensure that his lethal injection will not entail cruel and unusual punishment," the state asserted. "This is a red herring and a tactic for delay."

Columbia University law professor James S. Liebman, who has studied capital convictions and appeals across the country, expected the Alabama case to portend the Supreme Court's response. Like Nelson, he noted, Oken was not fighting the state's right to execute him, or its right to employ lethal injection. And, like Nelson, Oken contended that officials withheld key information about their plan until just before his execution date.

Liebman predicted that the execution stay would hold.

Last night, he said the justices' action clearly signaled how restrictive they consider their previous ruling. "It just indicates that a good majority of the court thought Nelson was narrow and applies to a very narrow set of circumstances," Liebman said.

Staff writer Lori Montgomery contributed to this report.

Oken was sentenced to death for the 1987 murder of Dawn Marie Garvin.Vince Culotta celebrates outside the prison in Baltimore after the U.S. Supreme Court decision to vacate the stay of execution for Steven Oken.