The U.S. Supreme Court stayed the execution of Lonnie Weeks Jr. last night two hours before he was scheduled to die by injection for the 1993 slaying of a Virginia state trooper in Prince William County.

The court acted on the basis of a petition filed by Weeks's attorneys that contends that instructions a judge gave to jurors at his trial regarding the death penalty were confusing. The Supreme Court, which begins a new session Oct. 4, probably will hear arguments in Weeks's case later this year or early next year, and a decision could be expected before next summer.

Weeks, 27, was condemned after he was convicted of murdering Trooper Jose M. Cavazos, who stopped Weeks and his uncle for a speeding violation on an Interstate 95 ramp outside Dale City on Feb. 24, 1993. The two men had been driving a stolen Volkswagen Jetta, and Weeks fired at Cavazos with a 9mm semiautomatic handgun after being ordered out of the car, hitting the trooper in the upper chest and arms.

A jury decided on death for Weeks after emotional testimony from Cavazos's wife, Linda. Weeks admitted to the killing hours after he was arrested, and he told Prince William authorities that he shot Cavazos after an "evil spirit" momentarily possessed him.

Timothy M. Richardson, of Virginia Beach, one of the defense attorneys, said last night that his argument before the Supreme Court will center on instructions given the jury in the sentencing phase of Weeks's trial. Richardson said jurors were confused by a particular instruction and asked the judge whether they were required to sentence Weeks to death; the judge told jurors simply to reread the instruction.

"If the jury says, in essence, they are confused by this instruction, for the court to say to go reread this instruction, it doesn't clear up that confusion," Richardson said in a telephone interview. "The Supreme Court has recognized that it's an important question of constitutional law on which they should speak. There is, at least, some positive sign that they are willing to hear the question."

The Supreme Court will not rule on any factual matters involved in the case, and its ruling will not affect Weeks's murder conviction. The court could, however, order a new sentencing hearing.

Richardson said last night that he and his co-counsel have sworn affidavits from two jurors who sat on the Weeks panel, both of whom say that they wanted to sentence Weeks to life in prison. Richardson said both jurors have indicated that they were confused and were "somehow led to come to the conclusion of the rest of the jury."

A jury's decision for a death sentence must be unanimous.

Richardson said he forwarded the two affidavits to Gov. James S. Gilmore III (R) as part of a clemency petition. Gilmore made no public statement regarding the stay order; the court's grant of a stay meant that the clemency petition was not officially before him.

In recent weeks, Cavazos's two children wrote letters to Gilmore, asking him to grant clemency to Weeks and requesting that their father's killer remain behind bars for the rest of his life. Leslie Cavazos-Amalgia, 26, of Los Angeles, and Trevor Cavazos, 23, of Fairfax, wrote of the pain they have felt since losing their father and their wish to see Weeks punished, but they also asked that he not be put to death.

Cavazos's widow has supported the death sentence for Weeks and has lobbied against allowing easy access to weapons such as the one used in her husband's murder.

In a telephone interview from Los Angeles yesterday, Leslie Cavazos-Almagia said that even though family members are somewhat split on the issue, they are in no way in a "feud" over Weeks's execution. Cavazos-Almagia said she and her brother have come to the conclusion that capital punishment does not make sense, calling it "unfair," while they also understand their mother's opinion that Weeks should face whatever punishment a jury gave him.

"It's hard to get people to understand why we think the way we do, and most people will never see it our way," Cavazos-Almagia said, hours before the scheduled execution. "I think a jail term of life is good enough because I think that's definitely what he deserves. He's going to have to pay. I just don't want any more violence associated with my father's death. It was violent enough."

Weeks, of Fayetteville, N.C., had been on probation in North Carolina on drug charges at the time of the killing and shot Cavazos with a gun that had been used earlier in a North Carolina slaying.

Richardson said last night that Weeks, who has expressed remorse to Cavazos's family, is looking forward to playing a continued "active role" in the rearing of his two children, who are 8 and 10 years old.

Louis Jefferson Dukes Jr., of the District, who was driving the car at the time of the slaying, was convicted of murder sentenced to life in prison.

Cavazos, 50, was a highly regarded member of the force who got the nickname "Poppa" after joining the state police at age 42. When he died, he was the first Virginia trooper killed since 1989; since Cavazos's death, two other troopers have been killed in the line of duty, both in traffic accidents.

State police erected a sign dedicated to Cavazos at the Dale Boulevard overpass at Interstate 95 in Feb. 1998.

Last night's stay was the second time in less than a month that a court has postponed an execution in Virginia. The Virginia Supreme Court stayed the execution of murderer Steve Edward Roach on Aug. 6, after he made arguments that prosecutors and a juvenile court judge violated state law by failing to notify both of his parents of a hearing.

Staff writer Joan Biskupic contributed to this report.

CAPTION: Linda Cavazos, wife of a slain Virginia state trooper, in 1995.

CAPTION: Lonnie Weeks Jr. will have a hearing later this year or early next year.