The death of Clayton Derrell Lockett occurred on April 29, 2014, when he suffered a heart attack during an execution by lethal injection in the U.S. state of Oklahoma.

He writhed, groaned, convulsed,[3] and spoke during the process and attempted to rise from the execution table fourteen minutes into the procedure, despite having been declared unconscious.

His mother left him when he was three years old, and he was then raised by his father who severely physically abused Lockett throughout his childhood, forced drugs upon him starting at age three, and taught him to steal without being caught.

[5][6][7] In 1992, at the age of sixteen, Lockett pleaded guilty in Kay County to burglary and knowingly concealing stolen property.

From 1890 to 2010, the rate of botched[a] lethal injections in the United States was 7.1%, higher than any other form of execution, with firing squads at 0%, the electric chair at 1.9%, hanging at 3.1%, and the gas chamber at 5.4%.

"Virtually all" death rows in the US were left without a steady supply of the drug, which is used to numb the pain of potassium chloride stopping the heart.

The Drug Enforcement Administration seized supplies of sodium thiopental from several states in spring and summer 2011, questioning how they were imported.

[14][15] Due to the supply issues, Oklahoma used an untested mixture of midazolam (to make the victim fall unconscious), vecuronium bromide (to paralyse), and potassium chloride (used to stop the heart) for Lockett's execution.

Republican allies of Fallin started impeachment proceedings against the justices who tried to delay the execution;[21] the stay was later lifted.

Lockett's lawyers also unsuccessfully sought to force Oklahoma to reveal the source of the drugs, which the state refused.

She asked for help from a doctor in attendance, Johnny Zellmer, who tried three times to get the IV into the jugular vein in Lockett's neck but failed.

After Lockett was declared unconscious at 6:33 p.m., the next two drugs, vecuronium bromide (paralytic) and potassium chloride (to stop the heart beating), were injected.

However, at 6:36 p.m., three minutes after being declared unconscious, Lockett started to struggle violently and was able to raise his head and speak, saying "Oh, man", "I'm not..." and according to some sources "something's wrong".

"[18] Oklahoma Department of Corrections Director Robert Patton said one of the doctors present stopped the execution when it became clear Lockett had a "vein failure".

Governor of Oklahoma Mary Fallin also requested a review of the execution process involved in Lockett's death.

[33] Dean Sanderford, Lockett's lawyer, witnessed the execution and expressed concern that "the planned review would not be independent".

He feared the planned review could “lead to suppression of critical evidence in the unlikely event that criminal wrongdoing is uncovered.”[35] A timeline issued by Robert Patton, director of the Oklahoma Department of Corrections, revealed that Clayton Lockett was tasered after refusing to be restrained and escorted to a medical room for an X-ray exam as part of the protocol leading up to his execution.

[34] President Barack Obama declared the action "deeply disturbing" and ordered attorney general Eric Holder to review the policy on executions.

[37] Obama cited uneven application of the death penalty in the United States, including racial bias (Lockett was African-American) and cases in which murder convictions were later overturned, as grounds for further study of the issue.

[38][39] Media coverage portrayed the execution as "botched", The Telegraph calling it "barbarism" and "inappropriate in a civilized society", noting "the idea of actually spectating while the victim is killed surely clashes with basic humanity.

It said "its use undermines human dignity, there is no conclusive evidence of its deterrent value, and any miscarriage of justice leading to its imposition is irreversible and irreparable" and called on the United States to cease its use.

Ryan Kiesel, the executive director of the American Civil Liberties Union of Oklahoma, said that by using a “science experiment” to cause Lockett to "die in pain" over the course of more than 40 minutes, the state had “disgraced itself before the nation and world”.

[34] US advocacy director of Human Rights Watch Antonio Ginatta said "people convicted of crimes should not be test subjects for a state’s grisly experiments" and that the "botched execution was nothing less than state-sanctioned torture".