The sheriff in this bucolic county seat 80 miles west of the District of Columbia "didn't want to get involved" in a land dispute that led to the shotgun slaying last year of a 35-year-old farm manager, a defense lawyer for Diane E. Kidwell told a Circuit Court jury today.

The lawyer, John Dowd, said in an opening argument that Kidwell telephoned Rappahannock County Sheriff W.A. Buntin on Nov. 9 for help in a border feud with her neighbor. Buntin, the elderly, white-haired chief law-enforcement officer here, told her instead to call her local attorney, Dowd said.

Dowd acknowledged that about 30 minutes later, Kidwell killed her neighbor's farm manager as he bore down on her with a bulldozer.

"We're not here to blame the sheriff," said Dowd. "He's ending a beautiful career here in Rappahannock County. But the fact is, he has the badge."

Buntin is scheduled to appear tomorrow as a prosecution witness.

Dowd said evidence in the trial will show that Kidwell "honestly and reasonably believed that farm manager Rance Spellman was going to kill her."

Spellman was employed by Patricia Saltonstall, a descendant of a prominent New England political family and owner of Points of View Farm near here. Saltonstall was involved in a dispute over a right-of-way that crossed property owned by Kidwell and her husband, Roger, at the time of the incident.

A special prosecutor in the case, former Fairfax assistant commonwealth's attorney Steven Merril, called the incident "an unnecessary killing . . . There's a lot of blame you can spread around in this case, but a life was taken and it didn't have to be." Merril said Spellman was armed with a rifle and a pistol concealed inside his shirt, but "never during the course of the entire incident were his weapons displayed. At his last breath they were still in their holsters."

Dowd contended Spellman, who he said had a reputation for "turbulence, violence and pugnacity," had started to reach inside his shirt when Kidwell fired a shotgun blast, striking him in the chest and killing him almost immediately.

Kidwell is a former employe of the Airlie Foundation near Warrenton, a conference center founded by former George Washington University professor Dr. Murdock Head. She was a key prosecution witness during Head's two bribery conspiracy trials in recent years. Her attorney, Dowd, was the head of a Justice Department strike force investigating organized crime at the time and also figured in the Head case.

Head, whose conviction was upheld three months ago by a U.S. appeals court, is currently in a federal prison in Alabama serving a 4 1/2-year sentence. At least two of his Airlie employes were in the courtroom here today as spectators.

Dowd said Kidwell will testify this week that Spellman threatened to "roll her over" with the bulldozer as she blocked his path with a pickup truck. "Someone had to act," Dowd argued.