SKIDMORE, Mo. — The murder of Ken Rex McElroy took place in plain view of dozens of residents of this small farm town, under the glare of the morning sun. But in a dramatic act of solidarity with the gunman, every witness, save the dead man’s wife, denied seeing who had pulled the trigger.

The killing was a shocking end for a notoriously brutal man who had terrorized the area for years with seeming impunity from the law until he was struck down in a moment of vigilante justice. It was also the first major case for a young county prosecutor, not far removed from law school and just months into the job, who said he was confident that the case would be solved soon.

But the silence of the townspeople held. Now, nearly 30 years later, that prosecutor, David A. Baird, is preparing to leave office with his first and most famous case still unsolved.

No one has ever been brought to trial in Mr. McElroy’s death, and, although there is no statute of limitations on murder, most people around here suspect that no one ever will be.