By Karen Brooks
AUSTIN, Texas (Reuters) - A man convicted of fatally shooting two people and paralyzing a third near Houston in 1998 is scheduled to be executed in Texas on Tuesday despite evidence that he is mentally disabled.
Milton Mathis, 32, has mental disabilities that should exempt him from the death penalty, according to officials who say he should be spared the death penalty. He was sentenced in 1999, before a Supreme Court ruled it unconstitutional to execute inmates with mental disabilities.
Mathis would be the 23rd person executed in the United States this year and the sixth executed in Texas.
He had appeals before the Supreme Court that were still pending on Tuesday morning, Texas prison officials said. Mathis has tried unsuccessfully to convince state and federal courts to halt his execution based on his mental disabilities.
Texas Republican Governor Rick Perry, who is considering a run for president, vetoed state legislation in 2001 that would have outlawed executing inmates with mental disabilities, saying that Texas juries should decide who to execute.
A year later, the Supreme Court issued its ruling in Atkins vs. Virginia, but left it to the states to determine how to decide whether a person had mental disabilities.
Mathis, who had an eighth-grade education when he was convicted, has scored in the low 60s on several IQ tests - including a 62 on a test administered by the state's prison system, according to an essay on the Stand Down Texas website by Mark White, a former Texas governor who opposes Mathis' execution. Stand Down Texas supports a death penalty moratorium in Texas.
Psychology experts have routinely put the standard for mental disabilities around a 70 IQ and lower.
"Mathis has suffered from obvious mental disabilities since childhood," White wrote. "He failed the first, fifth and eighth grades and dropped out of high school in ninth grade. He has had problems with functions that come easily to most of us, like dressing himself."
Mathis was convicted in September 1999 of opening fire on a home in Fort Bend County, west of Houston, and killing Travis Brown and Daniel Hibbard. A third victim, Melanie Almaguer, then 15, was also shot in the head and is paralyzed from the neck down.
Mathis also turned the gun on Almaguer's mother, who was in the home, but ran out of bullets, according to the state attorney general's office. He looted the home before setting it on fire, fled in Brown's car, and later told a fellow inmate that he wished he had "killed them all," according to the attorney general's office.
The execution is scheduled for after 6 p.m. Tuesday in Huntsville, Texas.
(Editing by Corrie MacLaggan and Greg McCune)