One of three men convicted for the murder in 1998 of James Byrd Jr, one of modern America's worst hate crimes, has been executed in Texas.
Byrd, a black man, was beaten, chained to a truck and dragged for miles by three white men.
His murder prompted Congress to pass hate crime legislation in 2009.
John William King, 44, an avowed white supremacist, is the second man to be executed over the killing. He had filed multiple appeals in the case.
On Monday, the Texas Board of Pardons and Parole voted unanimously to deny King a commutation or a 120-day reprieve.
Last October, the US Supreme Court declined to take up his appeal.
King was pronounced dead on Wednesday at 19:08 local time (23:08 GMT) at the Texas State Penitentiary in Huntsville.
Prosecutors depicted King, a self-professed racist with a criminal record, as the ringleader of the group of men who attacked Byrd.
Lawrence Russell Brewer, the other white supremacist who took part in Byrd's killing, was executed in 2011, although King had been sentenced earlier.
The third man, Shawn Allen Berry, was spared the death sentence and is serving a life term as he did not share the white supremacist beliefs of Brewer and King.
He will be up for parole in 2038, US media report.
In the early hours of 7 June 1998, in Jasper, Texas, Byrd, 49, encountered Brewer, King and Berry on the way home from a party.
The three men assaulted Byrd, then chained him by his ankles to the back of a pickup truck and dragged him for several miles until he was dismembered.
Police found parts of Byrd's body in front of a black church just outside the city; the rest was located over a mile away.
Authorities followed a blood trail of evidence - including a lighter engraved with "KKK" and King's nickname, Possum - placing the three men at the scene of the crime.
During King's trial, prosecutors showed evidence detailing his hatred of black people, including a letter he attempted to send Brewer in jail glorifying their murder, US media reported.
"Regardless of the outcome of this, we have made history and shall die proudly remembered if need be... Much Aryan love, respect, and honour, my brother in arms."
King had spoken of starting a race war and of initiating members of a white supremacist gang he belonged to by having them kidnap and murder black people, court documents showed.
He was convicted by a jury that deliberated for just over two hours.
The case sparked nationwide horror and outrage, and in 2001, Texas passed the James Byrd Jr Hate Crimes Act to toughen punishments for such crimes.
Congress followed, enacting the Matthew Shepard and James Byrd Jr Hate Crimes Prevention Act of 2009 to strengthen laws against crimes motivated by a person's race, colour, religion, sexual orientation, gender, disability or national origin.
King has repeatedly and unsuccessfully tried to appeal his case at the state and federal level. He has maintained he is innocent, blaming Berry alone for the murder, and arguing that his lawyers did not properly defend him.
Jasper's former sheriff, Billy Rowles, told KFDM News that King's execution would finally provide closure for the community.
"It's time... Most of the people in Jasper will believe this is the end of it."