(CNN) The US Supreme Court issued a stay of execution Tuesday night for a Georgia death row inmate who argued that a racist juror voted to put him to death because he is black.

Keith Tharpe, 59, was scheduled to die at 7 p.m. Tuesday night for the 1990 murder of his sister-in-law, Jacquelin Freeman. The justices granted the stay while they consider whether to take up his appeal. If the justices decide not to hear the case the stay will be lifted.

Conservative justices Clarence Thomas, Sam Alito and Neil Gorsuch dissented, saying they would not have granted the stay.

In post-conviction appeals, Tharpe did not deny killing Freeman. He sought a stay of execution based in part on racist comments from a juror who has since died.

In an interview seven years after Tharpe's sentencing, juror Barney Gattie used the n-word in reference to Tharpe and other black people and wondered "if black people even have souls." Tharpe's lawyers argued that a biased juror violated Tharpe's constitutional rights to a fair trial. Furthermore, his attorneys argued Tharpe is ineligible for execution because he is intellectually disabled.

Keith Tharpe shown in an undated booking photo from the Georgia Department of Corrections.

The Supreme Court of Georgia declined to hear Tharpe's claims on Tuesday, prompting his appeal to the US Supreme Court.

Tharpe convicted of shooting sister-in-law

Tharpe and his wife were estranged when the crime occurred on September 25, 1990.

Prosecutors said Tharpe stopped his wife and sister-in-law in the road as they drove to work, according to court records. He grabbed Freeman, his sister-in-law, from the vehicle and shot her before throwing her into a ditch and shooting her again, killing her.

Then, prosecutors alleged Tharpe raped his wife and took her to withdraw money from a credit union, where she was able to call police for help, according to the documents.

Three months later, after he was convicted of malice murder and kidnapping, Tharpe was sentenced to death.

Juror expressed racist views

Tharpe's appeal centered on the post-conviction testimony of Barney Gattie, a white juror in his trial.

During jury selection for the initial 1991 trial, Gattie told attorneys from both sides that he could be fair and impartial during the trial, said Brian Kammer, Tharpe's attorney with the Georgia Resource Center, a nonprofit that offers free legal representation to prisoners on death row,

Then, in May 1998, lawyers from Georgia Resource Center conducted interviews with each juror as part of a routine investigation to prepare for Tharpe's petition for habeas corpus, the process of determining whether his imprisonment was unlawful.

In his interview, Gattie showed that he "harbored very atrocious, racist views about black people," Kammer said.

According to his affidavit, Gattie said, "In my experience I have observed that there are two types of black people: 1. Black folks and 2. "N****rs."

Gattie went on to say in his affidavit, "I felt Tharpe, who wasn't in the 'good' black folks category in my book, should get the electric chair for what he did." As of 2001, Georgia carries out its executions by lethal injection.

"After studying the Bible, I have wondered if black people even have souls," Gattie said.

Gattie later said in a deposition that he did not intend to use the n-word as a racial slur, according to court documents.

Weeks after the interview, Tharpe's attorneys returned to Gattie's home and read his statements back to him, periodically stopping to ask him if the statements were accurate, court documents say.

Gattie had only one correction, but the rest of his statement stood, court documents filed by Tharpe's attorneys say. He signed the 1998 affidavit under oath.

JUST WATCHED How executions go wrong Replay More Videos ... MUST WATCH How executions go wrong 02:16

"He basically admitted his criteria for deciding to sentence Mr. Tharpe to death had much more to do with his race than any of the facts of the crime," Kammer said.

But two days later, the state -- doing "damage control," Kammer said -- came back to Gattie and had him sign a second affidavit that undercut his statements to Tharpe's attorneys, claiming Gattie was drunk at the time he made them.

But, Kammer argues, "he never denied that he in fact held the views that he stated in the initial testimony."

More claims of constitional violations

Gattie also said during jury selection he had no connection to Jacquelin Freeman's family. However, in the same affidavit in which he made the remarks in question, Gattie also admitted to knowing the Freemans.

Both of Gattie's false statements during jury selection -- that he could be fair, and that he had no connection to the case -- constitute violations of Tharpe's right to an impartial trial under the Sixth Amendment, Tharpe's attorneys claimed.

They also argued Tharpe, has an IQ of about 70, which would make him ineligible for execution under federal law, which bars the death sentence for people with intellectual disabilities.

Recent SCOTUS rulings could help Tharpe

Georgia law states that juror testimony cannot be used to impeach the verdict, or render it invalid -- even if it involves racial bias, Kammer said. At the time Gattie made the statements in question, this rule kept Tharpe's attorneys from being able to use them to prove his death sentence was the result of racial bias.

In Georgia, defendants can only receive a death sentence if the jury reaches the decision unanimously.

Kammer and his team relied on recent United States Supreme Court decisions to support their motion for a stay of execution.

The central one, Kammer told CNN, is Pena-Rodriguez v Colorado. In March, the US Supreme Court held in a 5-3 vote that laws like Georgia's are invalidated when a juror "makes a clear statement that indicates he or she relied on racial stereotypes or animus to convict a criminal defendant," Justice Anthony Kennedy wrote in the majority opinion.

Essentially, a juror's racial bias constitutes a violation of a defendant's rights to an impartial jury guaranteed by the Sixth Amendment, and prevents defendants from being able to prove a violation of their constitutional rights.

"A constitutional rule that racial bias in the justice system must be addressed -- including, in some instances, after the verdict has been entered -- is necessary to prevent a systemic loss of confidence in jury verdicts, a confidence that is a central premise of the Sixth Amendment trial right," Kennedy said.