The planned execution of two death row inmates in Oklahoma failed on Tuesday night, after one of the condemned men experienced complications during the lethal injections, and died of a heart attack instead. The second inmate who was scheduled to die two hours later, had his execution postponed, as a result. Read below for our earlier updates on this story.

Original post: After weeks of legal wrangling that culminated in various governors and courts wielding constitutional powers and threats of impeachment, two men will be killed tonight in a rare double execution -- Oklahoma's first since 1937.

Clayton Lockett was scheduled to die last Tuesday, but a last-minute stay of execution by the state's Supreme Court and the governor delayed it until today. Charles Warner was already scheduled to die today. Thus, the double execution. Lockett's will begin at 6 p.m. central time and Warner's at 8. 

As Guardian's Katie Fretland reports, the drug cocktail being used to kill the men -- midazolam, vecuronium bromide and potassium chloride -- has never been tested before in the low dosages that will be used tonight. Thus, the Oklahoma Department of Corrections warned that the executions might take longer to carry out. Just yesterday, Ohio announced that it would increase the dosage of drugs used in its executions after it took nearly a half hour for one inmate to die, during which time he appeared to be gasping for breath. Ohio maintained that the lower dosages were sufficient to kill a prisoner humanely.

Today, a small group of six people opposed to the death penalty staged a sit-in in Gov. Mary Fallin's office. A candlelight vigil will be held outside her house tonight.

Lockett wanted a steak dinner for his last meal, but it was over Oklahoma's $15 limit. An alternative meal from Western Sizzlin' was offered, but Lockett refused it. No doubt Western Sizzlin' is thrilled with this product placement. Warner's KFC chicken wings request was under the price limit, so he should get that.  

Lockett was convicted of the murder of 19-year-old Stephanie Neiman, who was buried alive, after Lockett shot her a shotgun. Warner was convicted of the rape and murder of Adriana Waller, an 11-month-old baby.

Update, 8:14 p.m.: Looks like there won't be a double execution tonight after all. According to Tulsa World's Cary Aspinwall, Lockett had a "vein failure." His execution was called off after about 40 minutes after he sat up and said "something's wrong." His current condition is unknown. Warner's execution, scheduled for later tonight, has been stayed.

Update, 8:26 p.m.: According to the AP's Bailey McBride, Lockett died at 7:06 p.m. central time, after suffering a heart attack. Warner's execution has been stayed for 14 days.

Update, 8:46 p.m.: More details from the AP: Lockett's execution was stopped about 20 minutes after the first drug was injected. He was described as "writhing on the gurney and shaking uncontrollably." All three drugs -- which had never been used in those dosages before tonight -- were administered.

Update, 9:45 p.m.: Gov. Mary Fallin, who once issued a stay of execution for Lockett (in order to try to circumvent the Supreme Court's stay), has now issued an "executive order" for a stay of execution for Warner of 14 days and requested that the Department of Corrections does a "full review" on what went wrong during Lockett's execution. Execution officials are saying Lockett was unconscious after the lethal injection drugs were administered and remained unconscious until his death, though this conflicts with witness reports.

Update, 10:00 p.m.: The AP's Bailey McBride has corrected her earlier tweets -- a prison official said "something's wrong," NOT Lockett. Other witnesses have reported that he mumbled and possibly said "man."