After a more than a five-year hiatus following a series of high-profile mistakes, Oklahoma is set to return to lethal injection when executions resume, possibly as soon as late 2020.

Here is our coverage of the death penalty in Oklahoma. 

An exterior view of the Oklahoma State Penitentiary in McAlester where death row is housed. SHANE BEVEL/The Frontier

March 14, 2018
Oklahoma will use nitrogen to carry out death sentences in wake of execution drug shortages

March 16, 2018
Study found Oklahoma could execute inmates using nitrogen without help from licensed medical professionals

April 26, 2019
Unable to purchase execution equipment, Oklahoma poised to build the device itself

May 15, 2019
DOC ‘getting closer’ to acquiring device necessary to carry out executions, director says

Nov. 16, 2019
Despite move to new cells, struggle over solitary confinement for death row prisoners continues

Jan. 15, 2020
Death penalty talks begin, but it’s unclear when executions will resume

Feb. 13, 2020
State officials reverse course, will end 5-year death penalty hiatus with return to lethal injection

Feb. 20, 2020
AG: Oklahoma prepared to ‘aggressively’ defend death penalty in upcoming federal court challenge

Feb. 27, 2020
Attorneys for death row inmates file motion, say 150-day stay is still in place

Death penalty timeline

April 29 – Clayton Darrell Lockett, 38, is executed. The execution was halted after a supposedly unconscious Lockett began speaking and writhing on the table. He died of a heart attack 43 minutes after the execution began. Charles Frederick Warner was set to be executed as well, but it was not carried out following the Lockett debacle.
Sept. 30 – After months of investigation and review, DOC releases its revised execution protocol. The protocol mirrors that of Arizona, where Director Robert Patton formerly worked.
Oct. 10 – DOC officials show off the renovated execution chamber at the Oklahoma State Penitentiary. More than $106,000 was spent on the renovation, most of which was spent updating the operations room and death chamber itself. So far it has been used only once.

Jan. 15 – Charles Frederick Warner, 47, is executed. It is later learned that a wrong drug — potassium acetate rather than potassium chloride — was used in his execution.
April 14 – Nitrogen gas inhalation adopted by state Legislature as execution option.
Sept. 16 – The Oklahoma Court of Criminal Appeals stays the execution of Richard Glossip mere hours before he was scheduled to die by lethal injection. A new execution date is set for Sept. 30.
Sept. 30 – DOC officials realize they have again purchased potassium acetate instead potassium chloride as they prepare to execute Richard Glossip later that day. Glossip’s execution was halted.
Oct. 2 – The Oklahoma Court of Criminal Appeals imposes indefinite stay on all executions.

Nov. 8 – Despite state’s recent problems conducting executions, not to mention the court-mandated stay, Oklahoma voters elect to enshrine executions in the state’s constitution. The vote ensures capital punishment will be available even if higher courts later rule lethal injection unconstitutional.

March 14 – Department of Corrections Director Joe Allbaugh announces DOC will use nitrogen gas as primary method of execution.

March 13 – Oklahoma Attorney General Mike Hunter tells television station KFOR that the delay in finishing the state’s new death penalty protocol is due to difficulties in finding a device that will administer nitrogen gas, saying that manufacturers of such devices are wary of public blowback.

March 28 – Hunter tells attendees at an Oklahoma District Attorneys Council meeting that, unable to purchase the equipment needed to administer nitrogen in an execution, the state would instead look to build its own device.

Feb. 13 — Hunter, flanked by Oklahoma Gov. Kevin Stitt and DOC director Scott Crow, says Oklahoma has secured a “reliable source” of lethal injection drugs and hopes to begin resuming executions in 2020. Hunter released a new death penalty protocol that Crow said had mostly minor changes that would ensure past mistakes are not repeated.

Feb. 20 — Hunter tells attendees at an Oklahoma District Attorneys Council meeting that the state is prepared to “aggressively defend” the death penalty in upcoming federal court challenges. 

Feb. 27 — Attorneys representing death row inmates file a motion to re-open their lawsuit against Oklahoma, alleging that the state did not sufficiently update their death penalty protocol. The attorneys argue that the 150-day court mandated stay on the setting of execution dates has not yet begun.