– For the first time since 2011, Missouri is set to execute a man on death row.

Gov. Jay Nixon on Monday denied a clemency request for Joseph Paul Franklin, a serial killer who shot a man outside a St. Louis synagogue in 1977. Franklin, now 62, targeted nearly two dozen African-Americans and Jews across the country in the late 1970s.

“As Governor, this is a power and a process I do not take lightly. Each instance involves a very specific set of facts, which must be considered on its own,” Nixon said of his decision. “This cowardly and calculated shooting was only one of many senseless acts of extreme violence that Franklin, motivated by racial and religious intolerance, committed against numerous victims across the country – from Tennessee and Ohio to Utah and Wisconsin.”

Instead of the typical three-drug cocktail the state has previously used to execute offenders, this execution is set to take place using pentobarbital, a sedative that, in high doses, causes respiratory arrest in humans. Missouri has received the drug from a compounding pharmacy, which has helped the state hide the distributor of the drug. The owner of pentobarbital, Denmark-based Lundbeck, is banned by its government from selling the drug for purposes of executions.

John Simon, an attorney for Franklin, said earlier this month that he was concerned that the drug could cause “a lengthy, excruciating death” in his call for Nixon to commute Franklin’s sentence.

“Criminal penalties aren’t intended to drag us down to the level of the worst offenders,” he said.

Missouri had been set to use propofol, the sedative found with Michael Jackson when he was found dead, but made a change last month when the European Union threatened to reduce exports if the drug was used in an execution.

The execution is set to take place at 12:01 a.m on Wednesday.