HUNTSVILLE, Texas — A federal appeals court halted a convicted Texas killer’s scheduled execution Tuesday so his lawyers can pursue appeals arguing he is mentally impaired and ineligible for the death penalty.
Robert James Campbell, 41, would have been the first US inmate executed since a botched execution in Oklahoma two weeks ago. His two appeals challenged the state’s plan to use a drug for which it will not reveal the source, as was the case with drugs used in Oklahoma.
‘‘I am happy. The Lord prevailed,’’ Campbell said from a cell just outside the Texas death chamber in Huntsville.
The US Court of Appeals for the Fifth Circuit halted his punishment about 2½ hours before he could have been taken to the death chamber, saying Campbell and his lawyers haven’t had a fair opportunity to develop the mental impairment assertions.
The appeal before the Fifth Circuit contended Campbell isn’t mentally competent for execution because he has an IQ of 69. Courts generally set a 70 IQ as the minimum threshold. Campbell’s lawyers, who went to the US Supreme Court with last-day appeals, filed a petition to the high court even before the Fifth Circuit ruled on the mental impairment issue.
Campbell was set to be executed for killing a 20-year-old Houston bank teller. His lawyers made an issue of the drug to be used in the execution and the source’s not being identified.
Like Oklahoma, Texas will not say where it gets its execution drugs, saying that it needs to protect the producer’s identity in order to prevent threats by opponents of the death penalty.
Halted for appeal
Unlike Oklahoma, which used a three-drug combination in the April 29 botched execution of Clayton Lockett, Texas uses a single dose of the sedative pentobarbital to kill inmates.
During Lockett’s lethal injection, the inmate’s vein collapsed, prompting Oklahoma prison officials to halt the procedure. Lockett later died of a heart attack.
The investigation is ongoing, but Oklahoma authorities have suggested the trouble started with Lockett’s vein rather than the drugs.
Campbell’s lawyers, however, are among several arguing the case demands greater execution-drug transparency.
Lockett writhed and grimaced after the lethal injection was administered, and corrections officials did not realize that not all the drug had entered his body for 21 minutes.
Campbell’s lawyers say Lockett’s failed execution proves what many inmates have argued since states turned to made-to-order drugs: that the drugs put the inmates at risk of being subjected to inhumane pain and suffering.
‘‘This is a crucial moment when Texas must recognize that death row prisoners can no longer presume safety unless full disclosure is compelled so that the courts can fully review the lethal injection drugs to be used and ensure that they are safe and legal,’’ said lawyer Maurie Levin.
Texas’s lawyers say Campbell’s assertions are speculative and fall ‘‘far short’’ of demonstrating a significant risk of severe pain.
‘‘The Constitution does not require the elimination of all risk of pain,’’ said Ellen Stewart-Klein, an assistant Texas attorney general.
Campbell’s execution would be the eighth this year for Texas, which kills more inmates than any other state, and the fourth in recent weeks to use the compounded pentobarbital.
Texas invoked confidentiality in late March when it obtained a new supply of pentobarbital to replace a stock that had reached its expiration date.
The Fifth Circuit rejected an appeal late Monday on the drug secrecy issue, saying mere speculation wasn’t enough to prove assertions Campbell could be subjected to unconstitutionally cruel pain if executed with drugs from Texas’s unidentified provider.
Campbell was convicted of capital murder for the 1991 slaying of Alexandra Rendon, who was abducted while putting gas into her car, robbed, raped, and shot.
‘‘This was not a shoot and rob and run away,’’ Rendon’s cousin, Israel Santana, said. ‘‘The agony she had to go through.’’
Rendon, who had been making wedding plans, was buried wearing her recently purchased wedding dress.