mistrial was declared late tonight in the murder trial of Diane E. Kidwell after the jury said it could not agree on whether Kidwell shot her neighbor's farm manager in self-defense during a land dispute last fall.

Jury foreman Eugene Leggett said afterward the panel was hopelessly deadlocked after more than seven hours of deliberation, with 11 members in favor of acquittal and a lone holdout arguing for conviction on a charge of voluntary manslaughter. The prosecution was seeking a first-degree murder conviction.

Circuit Court Judge Thomas Horne set a hearing for May 10 in Leesburg to determine whether and when Kidwell will be retried.

Kidwell testified on Thursday she shot 35-year-old Rance Spellman, an employe of Patricia Saltonstall's nearby Points of View Farm, as he bulldozed a disputed right-of-way across Kidwell's property last Nov. 9. But she contended she fired because she feared for her life as she blocked Spellman's way with a pickup truck.

Jury foreman Leggett, 57, president of a computer software company in Manassas, said, "Not everyone may understand the power--psychological and real--of a big bulldozer. It was a weapon in World War II and an effective one--more effective than tanks. It was a scary position she was in."

Spellman was driving a 43,000-pound tractor with a 13-foot blade toward Kidwell's truck when she fired a 12-gauge shotgun at him from a distance of about 20 feet, according to trial testimony.

In his closing arguments to the Rappahannock County jury, special prosecutor Steven A. Merril said Kidwell "had no right whatsoever to eliminate Rance Spellman from the face of the earth. . . She gave him the death penalty."

Defense lawyers John Dowd and Rodney Leffler countered during their closing arguments that Kidwell believed Spellman was armed and acted in self-defense when she fired the single blast that killed him. "She made a decision, a selfless and a courageous decision of a good and decent woman. . . ," said Dowd. "She took that gun. I'm glad she did."

A state police trooper who arrived minutes after the shooting found a loaded pistol concealed on Spellman's body and a sheathed rifle on the bulldozer, according to testimony in the three-day trial.

Merril today scoffed at arguments by Kidwell's lawyers as "a series of red herrings and smokescreens brought to you by the defense. . .The biggest smokescreen of all is the idea that this is self-defense. Kidwell fired a shot that hit right in the bullseye. Not a shot up in the air. Right in the chest."

Merril reminded jurors that under his cross-examination, Kidwell acknowledged on Thursday that her brother had warned her that Spellman might be armed but that she angrily refused to return to the house.

"Didn't you tell your brother: 'I'm going to stay here. Leave me alone. Don't fool with me'?" the prosecutor had asked. "Yes," Kidwell answered.

Merril contended evidence showed Spellman was wounded in the right chest, and did not support Kidwell's testimony that she saw Spellman reach with his right hand inside the left side of his shirt and feared that Spellman was going for a gun.

"It does not lie in the mouth of the prosecutor to talk about red herrings," Dowd responded, pounding emphatically on a courtroom railing. Saltonstall, the lawyer said, testified Spellman was "a professional" around guns. "He sure was. She said he maintained order on 'my mountain.' What is this, a gunslinger? A hired gun? Why did they have to keep order on that beautiful mountain? That's not the South Bronx . . . "

Dowd noted testimony by Kidwell that she had called the sheriff for help immediately before the incident and was told he "didn't want to get involved."

"At that point in the life of Diane Kidwell," Dowd continued, "there was no law except her own human reactions . . . " graphics/photo: DIANE E. KIDWELL ...judge declares a mistrial