Arkansas on Monday became the first state since 2000 to carry out a double execution. Two convicted murderers, Jack Jones and Marcel Williams, were put to death as part of an accelerated schedule because one of the state's lethal injection drugs expires at the end of April. A look at the procedures of multiple executions and their history in the U.S.:
HOW DID IT WORK?
Jones and Williams were scheduled to be executed 75 minutes apart Monday evening at the Cummins Unit prison at Varner, Arkansas, about 80 miles southeast of Little Rock.
Jones was executed on schedule, shortly after 7 p.m. Attorneys for the Williams persuaded a federal judge minutes later to briefly delay his execution over concerns about how the earlier one was carried out, claiming Jones "was moving his lips and gulping for air," an account the state's attorney general denied. The judge lifted her stay about an hour later and Williams was pronounced dead at 10:33 p.m.
Two double-executions were scheduled last week, but only a single inmate, Ledell Lee, was put to death. The other lethal injections were called off because of legal appeals.
Arkansas was the first state to do a double execution and the only state to do a triple execution following the 1976 Supreme Court decision that allowed the death penalty to resume.
In Arkansas' most recent triple execution, in 1997, only 51 minutes elapsed between the first two executions. The third came one hour and 50 minutes later.
WHAT'S THE HISTORY OF MULTIPLE EXECUTIONS?
The last state to put more than one inmate to death on the same day was Texas, which executed two killers in August 2000. Arkansas' last double execution occurred in 1999.
Oklahoma tried to conduct a double execution in 2014, but it was halted after the first prisoner writhed and moaned on the gurney during the botched attempt. The inmate, Clayton Lockett, died 43 minutes later of a heart attack.
There was a time when executing more than one prisoner on a single day was common. Records show at least seven states carried out multiple single-day executions in 1951.
In Texas, the nation's most active death penalty state, multiple executions were conducted 28 times starting in 1924, according to records.
WHY WOULD STATES DO IT THIS WAY?
Some attorneys and anti-death penalty groups have questioned whether stacking executions risks inflicting extra stress on prison staff and inviting mistakes.
But in court documents filed earlier this month, Wendy Kelley, director of the Arkansas Department of Correction, said having multiple executions on one night is better than setting separate dates "because the stress is more associated with an execution night than with a specific number of executions."
Jim Willett, the warden who helped carry out Texas' last multiple execution on the same day in 2000, said "if you can do it right once, why can't you do it twice the same day?"