Joseph Lewis Clark, 57, died at 11:26 a.m. Tuesday at the Southern Ohio Correctional Facility, nearly 90 minutes after the execution was to begin.
Even the condemned man complained about the delay.
"He said 'It don't work, it don't work, it don't work, it ain't working,' about 5 times," said witness Paul Kostyu.
The curtain behind a glass panel separating him from the area where witnesses watched the execution was pulled shut. Clark, sentenced to die for killing gas station attendant David Manning during a spree of robberies in 1984, could be heard moaning and groaning from behind the curtain.
When the curtain reopened at 11:17 a.m., about 40 minutes later, Clark had a shunt in his left arm and his eyes were closed as the execution continued. He raised his head from the gurney several times and breathed deeply before becoming still.
Prison officials later said his vein had collapsed.
Many death row inmates have claimed their executions could be painful, either because of the drug combination or because the procedure would not be handled by specially trained medical personnel.
"When you see situations like this, it gives rise to a cruel and unusual punishment claim," says CBSNews.com Legal Analyst Andrew Cohen. "A lawyer can stand up and say, 'Listen, even a condemned person, even someone who has been given society's worst punishment, shouldn't be put through this at the end.'"
On Friday, a federal judge in Columbus, Ohio, indefinitely postponed the execution of Jeffrey Hill, who is part of a death row lawsuit that claims Ohio's method of execution is cruel and unusual.
And the U.S. Supreme Court last week examined a Florida case that asks whether inmates can file last-minute civil rights challenges claiming lethal injection is cruel and unusual punishment. A ruling is expected before July.
The execution team Tuesday worked for about 25 minutes to find a vein in Clark's right arm before continuing with just the shunt in his left arm. At one point, a team member rolled up the leg of Clark's blue pants, looking for a vein in his right leg.
Prison procedures call for inserting two shunts, usually one in each arm, with one serving as a backup, prisons spokeswoman Andrea Dean said.
"This has never happened," Dean said of the delay, the longest since the state resumed executions in 1999.