By Steve Almasy, CNN

(CNN) - Forty years after they were convicted by a jury of firebombing a grocery store in Wilmington, North Carolina, civil rights activists who became known as the "Wilmington 10" were pardoned Monday by the state's outgoing governor.

"These convictions were tainted by naked racism and represent an ugly stain on North Carolina's criminal justice system that cannot be allowed to stand any longer," said Gov. Beverly Purdue. "Justice demands that this stain finally be removed."

In 1972, nine black men and one white woman were convicted in the store firebombing in the coastal city despite their claims of innocence and their supporters' vehement argument that the defendants were victims of racially biased prosecutors.

Their sentences were reduced in 1978 by the state's governor then, Jim Hunt, and two years later their convictions were overturned in federal court for reasons of misconduct by the prosecutors.

But until Monday there were no pardons, and the sting of the guilty verdicts still followed the six surviving members of the group that was known nationwide as the Wilmington 10.

Perdue said that among the key evidence that led her to grant pardons of innocence were recently discovered notes from the prosecutor who picked the jury. The notes showed the prosecutor preferred white jurors who might be members of the Ku Klux Klan and one black juror was described as an "Uncle Tom type."

Perdue also pointed to the federal court's ruling that the prosecutor knew his star witness lied on the witness stand. That witness and other witnesses recanted a few years after the trial.

Timothy Taylor, a North Carolina historian and a visiting professor at Duke University, said he was given the notes two years ago and started to go through them recently when the NAACP called again for pardons for the Wilmington 10.

"It was pretty shocking stuff," he told CNN on Monday.