The US Supreme Court has rejected a last-minute request by an Ohio death-row inmate to halt his execution.
Jay Scott (48), a schizophrenic man whose case has drawn the attention of the EU, had appealed for a stay of execution, and faced the death penalty last night.
Scott, who murdered a delicatessen owner in Cleveland, Ohio in 1983, had his execution halted minutes before he was to die in May, after a similar last minute reprieve a month earlier.
In a letter to the Governor of Ohio, Mr Robert Taft, on Tuesday the EU asked that Scott's life be spared, saying the execution would violate international standards of human rights.
"The European Union opposes the death penalty in all cases and promotes universal abolition," the letter said.
"We seek to ensure that executions in countries which are applying it are carried out in accordance with the minimum standards of human rights."
The letter was signed by Sweden, the current president of the EU, Belgium, which will take over the presidency next, and the European Commission.
Scott has a long history of untreated illness including schizophrenia.
He would be only the second person put to death in Ohio since the state reinstated capital punishment in 1981.
The central issue in his case has been whether his mental illness allows him to comprehend what is happening to him.
Scott was found guilty and sentenced to death for the killing during a robbery with three other men.
His lawyers argued that his original trial lawyers provided inadequate counsel by failing to raise the issue of his mental fitness during the sentencing phase that might have spared his life.
Meanwhile, a man who went on a 1995 shooting rampage in which three children were killed and four other people wounded was put to death by lethal injection on Wednesday in a Texas prison.
John Wheat (57), a former church custodian, was executed in Huntsville. He was the eighth person to be executed in Texas this year.
Wheat was the 247th person executed in Texas since the state resumed capital punishment in 1982, six years after the US Supreme Court lifted a ban on the death penalty.
Texas executed a record of 40 people last year. It has seven more executions scheduled for this year.