DOUBLE killer Edmund Zagorski has been executed by Tennessee in a "homemade" electric chair.

He was out to death last night at 7.26pm, amid fears it would be botched.

Zagorski, 63, shot and slit the throats of John Dotson and Jimmy Porter after they approached him to buy weed.

The last person to be put to death by electrocution in the US was Robert Gleason, who was executed in Virginia in 2013.

Zagorski picked the chair after his legal challenge to Tennessee's midazolam-based lethal injection protocol failed.

His attorneys say he believes death by electrocution will be quicker, but he maintains that both methods are unconstitutional.

The courts refused his bid for a Death Row reprieve 20 minutes before the execution.

Tennessee's chair hasn't been used since Daryl Holton chose to die this way in 2007.

The chair was built by a self-taught execution expert who is no longer welcome in the prison system and who worries that his device will malfunction.

Fred Leuchter had a successful career in the execution business before his reputation was destroyed by his claim that there were no gas chambers at Auschwitz.

Tennessee's chair is just one of many execution devices Leuchter worked on between 1979 and 1990, according to an article by Fordham University professor Deborah Denno in the William and Mary Law Review.

In addition to electric chairs, Leuchter built, refurbished and consulted on gas chambers, lethal injection machines and a gallows for at least 27 states.

After his comments about the Holocaust, it came to light that he had neither an engineering degree nor a license, even though he promoted himself as an engineer.

Despite this he stands by his death machine, saying his fears it will fail are due to changes others made to it after he was no longer allowed to service it.

Leuchter said: "What I'm worried about now is Tennessee's got an electric chair that's going to hurt someone or cause problems. And it's got my name on it.

"I don't think it's going to be humane."

Before the execution, Gov. Bill Haslam said he was confident the execution can be carried out without problems.

He said: "I have a great deal of confidence in our Department of Correction folks. ... We've spoken with them regularly and they've assured us" the chair is ready.

Zagorski has opted for a last meal of pickled pigs knuckles and tails before 1,750 volts shoot through him twice.

The dish is a traditional favourite in the southern United States.

Death row inmates are allowed £15 for a special meal before they're executed.