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Clayton Lockett: Oklahoma execution goes wrong

30 April 2014 Last updated at 13:14 BST

Prison officials in the US state of Oklahoma have halted an execution half way through, after botching the delivery of a new untested combination of drugs.

The prisoner, Clayton Lockett, was still said to be shaking uncontrollably 20 minutes after the first drug was administered. He later died of a heart attack.

Richard Lister reports.