The U.S. Supreme Court declined yesterday to review a death sentence imposed on a southside Virginia man convicted last year of raping and murdering a 61-year-old widow in a rural area of Lunenburg County.

The Court's decision left uncertain how soon Virginia authorities will face prospects of carrying out the first execution since the state's capital punishment law was revised two years ago. No one has died in Virginia's electric chair since 1962.

Yesterday's Supreme Court decision - which left unaltered a death sentence imposed on Alton Waye, 23, for the 1977 murder - was the second time the high court has refused to consider an appeal under Virginia's revamped death penalty statute. Two weeks ago, the supreme Court let stand a death sentence imposed on Michael M. Smith, a Williamsburg farm worker convicted of rape and murder.

Lawyers and state officials say no execution appears likely in Virginia for some time because further court appeals are expected. One of Waye's lawyers, William L. Wellons, said yesterday that they would consider asking the U.S. Supreme Court for a rehearing, along with other possible appeals. Smith's lawyer, David F. Pugh, has declined to comment, but other lawyers have said an appeal is expected.

Paul G. Edwards, Gov. John N. Dalton's press secretary, said yesterday that Dalton supports the death penalty but would consider any request for clemency "on the merits of each case."

Seven men - including James T. Clark Jr., who was convicted in the murder-for-hire killing of george Harold Scarborough in Fairfax County - have been sentenced to death under Virginia's revised statue.

They are imprisoned at the Mecklenburg Correctional Center, the state's maximum security prison. Virginia's electric chair and death chamber, located at the State Penitentiary at Richmond, have recently been cleaned repainted and repaired in preparation for the possible return of capital punishment.

No one has yet been sentenced to die under Maryland's recently revised death penalty law, according to state officials. The District of Columbia does not impose capital punishment. The only executions in the United States in recent years have been those of John Arthur Spenklink in Florida on May 25 and Gary Mark Gilmore in Utah on Jan 17, 1977. Both caused national controversies.

Yesterday, a jury in Southwest Virginia recommended what may be the eighth death sentence under the Virginia statute overhauled in 1977 to confirm with U.S. Supreme Court rulings on capital punishment. The Montgomery County Circuit Court jury proposed the death penalty for Buddy Earl Justus, 26, who was convicted last Wednesday in the Oct. 3, 1978, rape and slaying of a 21-year-old woman.

Judge Kenneth Devore said he would sentence Justus on July 3 after he received presentence reports. The judge is empowered to reduce the jury's recommendation to life imprisonment. Officials said Justus would soon be handed over to Florida authorities for prosecution on other charges.

Court reviews of other death sentences imposed in Virginia continued yesterday, as the state Supreme Court heard appeals from lawyers for two convicted killers - Clark, 22, found guilty in the Fairfax County murder-for-hire scheme, and Charles Sylvester Stamper, convicted of fatally shooting three persons during a Richmond-area restaurant robbery.

Under Virginia's capital punishment law, death sentences are automatically reviewed by the state Supreme Court. Officials said court decisions on the Clark and Stamper appeals are likely by late August. If their death sentences are sustained, the two men may then seek U.S. Supreme Court review.

Waye was convicted of brutally beating the Lunenburg County woman and stabbing her 42 times after he allegedly raped her. His trial was transferred to Mecklenburg County, where he was convicted by a Circuit Court jury. His lawyer argued that Waye lacked sufficient mental capacity to have carried out a premeditated murder.