The lawsuit also sites an Oct. 15, 2012, execution in which South Dakota death row inmate Eric Robert, 50, cleared his throat, gasped for air and then snored after receiving the lethal injection. His skin turned a purplish hue and his heart continued to beat for 10 minutes after he stopped breathing. It took 20 minutes for authorities to finally declare Robert dead.
"These events are consistent with receipt of a contaminated or sub-potent compounded drug," the lawsuit says.
Use of the same drug in Taylor's execution could result in a similar reaction, Hellman said.
"It is extremely disturbing," he said.
On Monday, Missouri Corrections Department Director George Lombardi told a legislative panel that the agency pays for the drug to be independently tested to make sure it works and is sterile. He also said the agency had found no substantial issues in a background check of its current supplier.
Lombardi did not release the name of the pharmacy that provides the drug, saying Missouri could not carry out lethal injections if that information were released. He said the state pays $8,000 in cash to the pharmacy for the drug.
Associated Press writers Ken Miller in Oklahoma City and Amy Shafer in Chicago contributed to this report.
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