An inmate on death row who tried to file a last-minute appeal against his execution in Texas was told: “We close at five.” Too late to plead, Michael Wayne Richard was put to death by lethal injection.

Last night the judge who refused to take his appeal was on trial for judicial misconduct. Judge Sharon Keller, dubbed “Sharon Killer” for her tough line on crime, could be removed as presiding judge of the Texas Court of Criminal Appeals.

The case has become a focus for criticism of the death penalty in America, with opponents of capital punishment protesting outside the court.

Mike McKetta, a special prosecutor for the state commission on judicial conduct, said: “When the government has a death penalty, it is essential that there be not the perception but the reality that it is administered error-free.”

Judge Keller, a former prosecutor, earned her nickname in 1998 when she rejected a new trial for Roy Criner, a man with learning disabilities who was convicted of rape, even though new DNA tests showed that the semen in the victim was not his.

“We can’t give new trials to everyone who establishes, after conviction, that they might be innocent,” she later told a television interviewer. “We would have no finality in the criminal justice system and finality is important.” Mr Criner was eventually pardoned by the then Texas Governor George W. Bush.

Judge Keller left work early on September 25, 2007, to meet a workman at her home. At about 4.45pm she received a telephone call from court to ask if the clerk’s office could stay open late. She said no.

Rindy Fox, a legal secretary for the Texas Defender Service, representing Richard, testified that she had three telephone conversations with the court’s deputy clerk, Abel Acosta, in which she made clear that defence lawyers were having computer problems.

At 5.56pm Ms Fox called the court to say that the 31-page appeal was printed and ready to lodge with the court. “I said, ‘Abel I got it ready to file, I’m coming down’. He said, ‘Don’t bother, we’re closed’,” Ms Fox testified.

Richard, who was convicted of the rape and murder in 1986 of a nurse and mother of seven in Houston, was executed at 8.23pm. His last words were: “Let’s ride. I guess this is it.”

He was the 405th prisoner put to death in Texas, America’s busiest death-penalty state, since 1982.

The defence team had sought to file the appeal in response to a decision by the US Supreme Court that morning to review execution by a lethal injection of a three-drug cocktail to determine whether it violated the constitutional ban on “cruel and unusual punishment”. The review put executions on hold across America for more than six months before the justices upheld the technique.

Judge Keller, 56, a Roman Catholic and a Republican appointee who has served at the court since 1994, says she was never given a reason for the request to keep the court open. “If there had been some comment about computer problems I would have started thinking in a different direction,” she said in a deposition in June.

Chip Babcock, her lawyer, said that defence lawyers could file appeals directly to judges. He said that another judge on duty that night may have known about Richard’s impending appeal. That judge denies the claim.

“This whole case is about the confusion between the word ‘court’ and ‘clerk’,” Mr Babcock said. “There is no question the clerk’s office closes at 5. That does not mean there are not after-hours filings.”

At last night’s “special master” hearing Judge Keller insisted that a request for time did not fall within the rules. “I think it’s a close call, but I think that’s right,” she said.

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