Joseph Paul Franklin, a white supremacist serial killer who was convicted of eight racially motivated murders across the United States, was executed early Wednesday. He was 63.

Franklin was executed by a lethal dose of the barbiturate pentobarbital, which is commonly administered alongside two other drugs. It was the first time a Missouri death row inmate was executed by that drug alone, although it has been used in other states, to the dismay of human rights activists.

Court appeals delayed Franklin’s execution by hours. The Missouri Department of Public Safety stated that he was given the dose at 6:07 a.m. ET, and was pronounced dead 10 minutes later. Franklin did not give a final statement and also reportedly refused a final meal.

Franklin, a neo-Nazi and member of the Ku Klux Klan, eventually claimed responsibility for as many as 20 murders, but due to his changing accounts of events, law enforcement officials have been unable to verify exactly how many crimes he committed. According to USA Today, he was serving six life sentences but was put to death for only one of those murders, a sniper shooting at a Missouri synagogue in 1977.

Franklin admitted to hiding on a grassy knoll outside of the Richmond Heights temple Brith Shalom armed with a telescopic hunting rifle. When worshippers began exiting the synagogue, Franklin started to shoot, killing 42-year-old Gerald C. Gordon and wounding two others, the St. Louis Post-Dispatch reported.

Franklin’s execution took place two days after he was denied clemency by Missouri Gov. Jay Nixon on Monday. Nixon said that Franklin had committed "merciless acts of violence, fueled by hate."

In addition to the murders, Franklin also confessed to attempted assassinations of civil rights leader Vernon Jordan and Larry Flynt, the publisher of Hustler magazine. Franklin later said in a police confession that he shot Flynt in retribution for a Hustler pictorial that portrayed interracial sex. Flynt was shot and permanently paralyzed by Franklin in Georgia in 1978, but protested the execution last month.

In a column for the Hollywood Reporter, Flynt wrote that he had “every reason to be overjoyed with this decision,” but wasn’t. “I have had many years in this wheelchair to think about this very topic,” Flynt wrote. “As I see it, the sole motivating factor behind the death penalty is vengeance, not justice, and I firmly believe that a government that forbids killing among its citizens should not be in the business of killing people itself.”

But the family members of two teenage cousins who were killed by Franklin in 1980 feel differently. Abbie Evans Clark, who lost her 13-year-old son Dante Evans Brown to Franklin, told the Cincinnati Ohio News that she would be glad to be the one to administer the lethal dose.

“Yes, I would, God forgive me,” she said. “Maybe God will forgive him, but right now I can’t. They say you should forgive but at this time, I should pray on that because I don’t feel that way."