An avowed racist who orchestrated one of the most gruesome hate crimes in US history was executed on Wednesday in Texas for the dragging death of a black man.

John William King, who was white, received lethal injection for the slaying nearly 21 years ago of James Byrd jnr, who was chained to the back of a truck and dragged for nearly 5km along a secluded road in the piney woods outside Jasper, Texas.

The 49-year-old Byrd was alive for at least 3km before his body was ripped to pieces in the early morning hours of June 7, 1998.

Prosecutors said Byrd was targeted because he was black.

King was openly racist and had offensive tattoos on his body, including one of a black man with a noose around his neck hanging from a tree, according to authorities.

Busiest capital punishment state

King, 44, was put to death at the state penitentiary in Huntsville, Texas. He was the fourth inmate executed this year in the US and the third in Texas, the nation's busiest capital punishment state.

King kept his eyes closed as witnesses arrived in the death chamber and never turned his head toward relatives of his victim.

Asked by Warden Bill Lewis if he had a final statement, King replied: "No."

Within seconds, the lethal dose of the sedative pentobarbital began taking effect. He took a few barely audible breaths and had no other movement.

He was pronounced dead at 19:08 CDT, 12 minutes after the drug began.

In a statement released after his execution, King said: "Capital punishment: them without the capital get the punishment."

Byrd's sister, Clara Taylor, who watched King die, said he "showed no remorse then and showed no remorse tonight".

"The execution for his crime was just punishment," she said. "I felt nothing - no sense of relief, no sense of happy this is over with."

As witnesses emerged from the prison, about two dozen people standing down the street began to cheer.

The killing of Byrd was a hate crime that put a national spotlight on Jasper, a town of about 7 600 residents near the Texas-Louisiana border that was branded with a racist stigma it has tried to shake off ever since.

Local officials say the reputation is undeserved.

KEEP UPDATED on the latest news by subscribing to our FREE newsletter.

- FOLLOW News24 on Twitter