Attorneys for convicted killer Russell Bucklew are asking a federal court to put his execution on hold, citing concerns that lethal injection could cause a painful death due to a rare medical condition.
The stay request was filed Wednesday in U.S. District Court in Kansas City, Missouri.
Bucklew is scheduled to die at 12:01 a.m. May 21 for killing a romantic rival during a violent crime spree in southeast Missouri in 1996.
The execution would be the first since Oklahoma inmate Clayton Lockett's vein collapsed and he suffered a fatal heart attack more than 40 minutes after his execution began last month.
Bucklew's attorneys say he suffers from cavernous hemangioma, which causes weakened and malformed blood vessels.
A spokeswoman for Missouri Attorney General Chris Koster declined comment.
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