Oklahoma, as of Monday, did not have the drugs needed to conduct an execution scheduled for this week but aims to obtain chemicals for the lethal injection by the time the death sentence is to be implemented on Thursday, officials said.
Several states, including Oklahoma, have had difficulty getting drugs used in the lethal injections after pharmaceutical companies, especially in Europe, clamped down on sales for executions due to opposition to capital punishment.
According to court documents filed by the state on Monday, the Oklahoma Department of Corrections "remains without the drugs to carry out the lawful sentences of death" for two inmates the state plans to execute this month.
Attorneys for inmates Clayton Lockett, who is scheduled to be executed on Thursday, and Charles Warner, who is scheduled to be executed on March 27, requested their death sentences be put on hold due to uncertainty over the drugs.
The state attorney general's office would not speculate on what would happen if the drugs were not found by the time Lockett is due to be executed.
"The Attorney General's Office is exhausting all available options to ensure the punishment for this heinous crime is carried out," spokesman Aaron Cooper said in a statement.
Lockett was convicted for the 1999 shooting death of a 19-year-old woman. The victim was among those who were kidnapped by three attackers, including Lockett, and buried in a shallow grave.
Oklahoma uses three main drugs to carry out its executions, the sedative pentobarbital, vecuronium bromide, which stops respiration, and potassium chloride, which stops the heart, according to the state's department of corrections.
Several U.S. states, including Missouri, Ohio, Florida and Georgia have been turning to lightly regulated compounding pharmacies for drugs to use in lethal injections after pharmaceutical companies stopped allowing sales of their drugs for executions.
Advocates for inmates in several states have launched court challenges saying the compounding pharmacy drugs can lack purity and potency and cause undue suffering that violates the U.S. Constitution's protections against cruel and unusual punishment.
© 2015 Thomson/Reuters. All rights reserved.