WASHINGTON

Charles Dean Hood was sentenced to death in 1990 by a Texas judge who had been sleeping with the prosecutor in his case. It took Mr. Hood almost 20 years to establish that fact.

But he finally managed to force the two officials to testify about their rumored affair in the fall of 2008. They admitted it.

Texas’s highest court for criminal matters, its Court of Criminal Appeals, considered all of this and concluded that Mr. Hood should be executed anyway. In a 6-to-3 decision in September, the court told Mr. Hood that he had taken too long to raise the issue of whether a love affair between a judge and a prosecutor amounted to a conflict of interest.

Mr. Hood has asked the United States Supreme Court to hear his case. On Thursday, 21 former judges and prosecutors filed a brief supporting him. So did 30 experts in legal ethics.