Marvin Wilson was always slow.
Growing up in extreme poverty in east Texas in the 1960s, he struggled with basic tasks, like tying his shoes, counting money, and mowing the lawn. He fared miserably in school, earning D's and F's in special education classes and failing the 7th grade. The other kids called him "dummy" and "retarded." He was socially promoted to the 10th grade, then dropped out for good.
As an adult, he did manual labor and had a son with a common-law wife. But he remained extraordinarily childlike, according to his younger sister, Kim Armstrong.
"I couldn't believe it when I saw him still sucking his thumb when his son was born," Armstrong said in a 2003 affidavit. "Marvin was in his twenties."
Yet Wilson, now 53, was not slow enough for the Texas and federal courts that authorized his death by lethal injection next week for a 1992 drug-related murder. They have ruled that he is not covered by a 2002 Supreme Court ruling prohibiting the execution of the mentally retarded.
Human rights groups, legal experts and a Texas state senator denounced the imminent execution as a clear flouting of the law, while Wilson's attorneys have filed a last-ditch appeal with the Supreme Court, and requested a stay of execution from the Texas Board of Pardons and Gov. Rick Perry.
In their bid to halt the execution, Wilson's allies point to a 2004 psychological exam that measured his IQ at just 61. In Texas, the benchmark for mental retardation is an IQ of about 70 or below. Other states use a threshold IQ of 75 or lower.
"This case really does very much push the line," said Paul Campos, a professor at the University of Colorado Law School, who is not involved with Wilson's defense. "We're talking about a mental child."
But Texas prosecutors saw things differently, arguing successfully that Wilson was a street-smart drug dealer who had the acumen to seek vengeance against a man who betrayed him to the police.
In 1992, Wilson was arrested and charged with killing of Jerry Williams, a drug informant. Four days before his death, Williams provided information to police in Beaumont, Texas, that led to Wilson's arrest for cocaine possession.
Witnesses testified that they saw Wilson abduct Williams from a gas station with the help of another man, Terry Lewis. The three men drove off in the direction of a local oil refinery. The next day, Williams was found dead, with bullets wounds in his neck and head. No forensic evidence or eyewitnesses established who pulled the trigger.
Both Wilson and Lewis were tried for murder. Lewis was sentenced to life in prison with the possibility of parole. Wilson was sentenced to die.
The crucial evidence establishing Wilson as the shooter came from Lewis's wife, who testified that Wilson told her that he pulled the trigger, not her husband.
"She said Marvin confessed to her," said Lee Kovarsky, Wilson's attorney and a law professor at the University of Maryland. "Her testimony put Marvin on death row, as opposed to her husband."
Campos, the professor, said the circumstances of Wilson's conviction left significant room for doubt about his exact culpability in the crime. The lack of any aggravating factors -- the murder was not especially heinous or cruel, and did not involve multiple victims, a child or police officer -- also made it a good case for leniency on the basis of Wilson's mental deficits, he said.
"Obviously all murders are serious, but we're talking about a drug murder under ambiguous circumstances," he said. "This is just a very ordinary homicide, with a clearly mentally disabled defendant."
Yet in a series of rulings since 2002, Texas courts rejected expert testimony and evidence from Wilson's defense team, including his score of 61 on a standard IQ test, that seemed to establish him as mildly retarded.
The courts sided instead with state prosecutors, who argued that the IQ test was improperly administered, and that Wilson's behavior showed a man of normal intelligence. A federal appellate court, the 5th Circuit Court of Appeals, declined to overturn the state's decision.
The 5th Circuit justices did find that the evidence of Wilson's retardation was "mixed" and that "other fact-finders might reach a different conclusion as to whether Wilson is mentally retarded on the evidence before the state." But the court said that under current law it was bound to accept the Texas ruling and allow the execution to proceed.
Unless the Supreme Court or Texas officials intervene, Wilson's legal battles will be over soon. He is scheduled to die by lethal injection in the Texas death chamber in Huntsville next Tuesday evening.
The Supreme Court has been asked before to revisit its 2002 ruling, known as Atkins v. Virginia, which left it to the states to formulate the standards determining which inmates qualified as mentally retarded, but has repeatedly declined to do so.
Kovarsky said a failure of the Court to take Wilson's case will prove that the Atkins decision "has become a hollow rule."
Rick Perry, the Texas governor, is also unlikely to step in. In 2001, Perry vetoed a bill that had passed both houses of the state legislature, with bipartisan support, outlawing the execution of the mentally retarded. Perry appointed all of the members of the Texas Board of Pardons and Parole, which has almost never granted a reprieve to a condemned prisoner during his administration.
On Friday afternoon, Rodney Ellis, a Texas state senator who authored the 2001 bill vetoed by Perry, issued a statement denouncing the scheduled execution of Wilson.
"We do not execute children in the state of Texas, therefore we should not execute those who have the mental capacity of a child," Ellis said. "The ultimate penalty should be reserved for those that can clearly comprehend why they are going to die."