Texas has executed a 44-year-old man for raping and murdering an 11-year-old girl, despite pleas from his attorneys he is too mentally impaired to qualify for capital punishment.

The execution had been delayed briefly while attorneys for Bobby Wayne Woods asked the U.S. Supreme Court to halt the lethal injection pending a court ruling.

Justices denied Woods' last-ditch appeal just after 6 p.m. CST, just before his scheduled execution for the death of Sarah Patterson.

Woods, 44, had been transferred 45 miles from his death row cell at the Polunsky Unit near Livingston to a holding cell in Huntsville, a short walk from the death chamber.

Woods' attorney had argued that Woods was mentally impaired and ineligible for execution under court guidelines, and that previous appeals to spare Woods' life were unsuccessful because of shoddy work by his lawyers at the time.

Tests administered to Woods have put his IQ anywhere from the 60s to the 80s. An IQ of 70 is considered the threshold for mental impairment.

Woods was convicted of capital murder and sentenced to die for the April 1997 slaying of Patterson, his ex-girlfriend's daughter. She and her 9-year-old brother were snatched from their home in Granbury, near Fort Worth. Sarah's throat was slit with a knife. Her brother was beaten and left for dead but survived to testify against Woods.

The execution would be the 24th and last scheduled for this year in Texas, where 18 inmates received lethal injection in 2008 in the nation's busiest capital punishment state. At least five already are scheduled for 2010, including two in January.

In an appeal to the Supreme Court, Woods' lawyer, University of Texas law professor Maurie Levin, argued the performance of Woods' state-appointed attorney during earlier appeals was "so egregious" the prisoner's mental impairment claims could not be accurately assessed. She pointed out the attorney has since been removed from a list of lawyers eligible to represent condemned inmates but by the time she got the case, "the damage had been done."

State attorneys told the high court no constitutional right exists for an inmate to have an effective appeals attorney and Woods' claim of due-process violations "does not change that fact." They also argued Woods' mental impairment claims already have been rejected by the courts and the last-ditch appeals improperly duplicated those rejections.

Woods blamed Patterson's death on a cousin who subsequently committed suicide. He said injuries to her brother were the result of an accident.

"We went walking around graveyards, horsing around by a fence," Woods told The Associated Press last year from death row. "Cody jumped on my back and hit a fence post.

"I guess I panicked."

At his trial, Cody Patterson testified Woods attacked him, and prosecutors presented a mountain of evidence implicating Woods in Sarah's killing, including signed confessions.

Richard Hattox, the former Hood County district attorney who prosecuted Woods, said authorities also had DNA evidence of the girl's blood on Woods' knife, her blood on his shoe and his DNA on her panties, which were found in Woods' car.

"How could there be little doubt?" Hattox said Wednesday. "Every bit of his appeal effort has been expended toward his claim of retardation. And there's no proof he is retarded."