Texas, the nation's busiest death penalty state, is set to mark a solemn moment in criminal justice Wednesday with the execution of convicted killer Kimberly McCarthy.

If McCarthy is put to death in Huntsville as planned, she would become the 500th person executed in Texas since the state resumed carrying out the death penalty in 1982. The 52-year-old also would be the first woman executed in the U.S. since 2010.

McCarthy's attorney, Maurie Levin, said she has exhausted all efforts to block the execution, after denials by the Texas Court of Criminal Appeals.

"If there was something to appeal, I would," said Levin.

Texas has carried out nearly 40 percent of the more than 1,300 executions in U.S. since the Supreme Court allowed capital punishment to resume in 1976. The state's standing stems from its size as the nation's second most populous state as well as its tradition of tough justice for killers.

With increased debate in recent years over wrongful convictions, some states have halted the practice entirely. However, 32 states have the death penalty on the books. Still, it's clear the debate over capital punishment has touched Texas, with lawmakers providing more sentencing options for juries and courts narrowing the cases for which death can be sought.

McCarthy faces execution for the 1997 robbery, beating and fatal stabbing of retired college psychology professor Dorothy Booth. Booth had agreed to give McCarthy a cup of sugar before she was attacked with a butcher knife at her home in Lancaster, about 15 miles south of Dallas. Authorities say McCarthy cut off Booth's finger to remove her wedding ring.

Police also had linked two other slayings to McCarthy, a former nursing home therapist who became addicted to crack cocaine.

In her appeals, McCarthy contended prosecutors improperly excluded black jurors and that her lawyers failed to challenge the moves at trial or in early appeals. McCarthy is black, and Booth was white. All but one of the 12 jurors at McCarthy's trial were white.

In January, McCarthy had been moved to a small holding cell a few steps from the Texas death chamber when a Dallas judge moved her execution to April. That timing then was reset for June when Dallas County District Attorney Craig Watkins said he wanted to await the outcome of capital punishment-related bills before lawmakers in Austin.

On Tuesday, the Texas Court of Criminal Appeals declined to reconsider its denial a day earlier of McCarthy's appeal, saying her claims should have been raised previously.

Levin, a University of Texas law professor, said because the court's ruling focused on a procedural and not a substantive issue, the case cannot be appealed to the U.S. Supreme Court.

"The shameful errors that plague Ms. McCarthy's case — race bias, ineffective counsel and courts unwilling to exercise meaningful oversight of the system — reflect problems that are central to the administration of the death penalty as a whole. For this to be the emblem of Texas' 500th execution is something all Texans should be ashamed of," Levin said.

McCarthy declined to speak with reporters as her execution date neared.

Anti-death penalty groups planned to protest outside the Walls Unit in Huntsville, where McCarthy is set to receive a lethal injection Wednesday evening.

"The whole world is looking at Texas," said Gloria Rubac, with the Texas Death Penalty Abolition Movement in Houston.

McCarthy would be the 13th woman nationwide and the fourth in Texas put to death since 1976. In the same period, more than 1,300 men have been executed nationwide, 496 of them in Texas. Virginia is a distant second, nearly 400 executions behind.

Federal statistics show that over the past three decades women account for about 10 percent of convicted murderers. According to the NAACP Legal Defense Fund, there were 63 women on death row in the U.S. as of Jan. 1, representing 2 percent of the nation's 3,125 condemned prisoners.

Prosecutors showed that McCarthy stole Booth's Mercedes and drove to Dallas, pawned the wedding ring she had removed from the woman's severed finger for $200 and then went to a crack house to buy cocaine. Evidence also showed she used Booth's credit cards at a liquor store.

Booth's DNA was found on a 10-inch butcher knife recovered from McCarthy's home.

McCarthy blamed the crime on two drug dealers, but there was no evidence either existed.

Blood DNA evidence also tied McCarthy to the December 1988 slayings of 81-year-old Maggie Harding and 85-year-old Jettie Lucas. Harding was stabbed and beaten with a meat tenderizer, while Lucas was beaten with both sides of a claw hammer and stabbed.

McCarthy, who denied any involvement in the attacks, was indicted but not tried for those slayings.

McCarthy is a former wife of Aaron Michaels, founder of the New Black Panther Party, and he testified on her behalf. They had separated before Booth's slaying.

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Follow Juan A. Lozano at http://www.twitter.com/juanlozano70.