Since executions were resumed in the United States in 1977 after a decade-long hiatus, 42 of the 153 people executed have been blacks who killed whites; until yesterday none have been of whites who killed blacks.

"The scandalous paucity of these cases, representing less than two-tenths of 1 percent of known executions, lends further support to the evidence that the death penalty in this country has been discriminatorily applied," the sociologist, Michael Radolet, wrote.

Statistics from the Federal Bureau of Investigation show that more than 90 percent of people convicted of murder or manslaughter in the United States are intraracial, whites killing whites or blacks killing blacks. The statistics suggest that in the last three years cases in which blacks killed whites were about twice as common as cases of whites killing blacks.

That would mean that slightly less than 3 percent of such slayings in the United States involve whites killing blacks, far more than the two-tenths of a percent of the executions of whites who killed blacks. 'The Tony Cimo Story'

Opponents of the death penalty said that a sidelight of the Gaskins case actually highlighted how profoundly race mattered in capital cases. They contrasted Mr. Gaskins's fate with that of the white man who hired him for the killing, Tony Cimo of Murrell's Inlet, S.C. Mr. Cimo was sentenced to eight years in prison but was released after serving only six months. He was portrayed on a CBS television movie, "Vengeance: The Tony Cimo Story."

Mr. Bruck called the arrangement "a high-tech lynching," and added: "About all you can say about South Carolina's efforts to correct racial disparities in this case is that Tony Cimo served six more months than he would have half a century ago.

"This is hardly evidence that South Carolina is protecting black lives more energetically than it used to," Mr. Bruck continued. "Gaskins's crime, after all, is that he killed his black victim before the state could get around to killing him itself."