By Karen Brooks
AUSTIN, Texas (Reuters) - Texas is set to execute on Thursday a convicted murderer who stabbed a teenager and her toddler cousin to death in an empty field near his Houston apartment complex and who has spent half of his life on Death Row.
Preston Hughes III, 46, is scheduled to die by lethal injection after 6 p.m. CST. Hughes, 46, was convicted of stabbing to death 15-year-old Shandra Charles and her 3-year-old cousin, Marcell Taylor, in September 1988.
He would be the 40th inmate to be executed in the United States this year, and the 15th in Texas - including a San Antonio man on Wednesday.
Hughes has maintained his innocence, first saying the deaths were an accident and then contending that he had nothing to do with them and that police had framed him. At the time, Hughes had been free on probation for the aggravated sexual assault of a 13-year-old girl.
There is no DNA evidence linking him directly to the killings, and advocates and Hughes' lawyer contend that there are too many weaknesses and that the evidence against him was either circumstantial or fabricated.
The 15-year-old girl and her cousin were found stabbed several times in the neck and chest, their jugular veins and aortas severed, according to an account by the Texas Attorney General's Office.
Authorities said Charles was still alive and told police that a man named Preston had stabbed her after trying to rape her. Critics of the case said Charles could not have stayed alive long enough to say anything to police.
Police found Hughes at his nearby apartment, along with a knife, some blood on his clothes, and Charles' eyeglasses on his couch, which Hughes later said was planted.
Hughes was convicted of capital murder by a Harris County jury during a trial in which the Houston police crime lab director was rebuked by the judge for waiting until he got into the courtroom to test a knife found in Hughes' apartment for blood - tests performed for the first time while jurors were waiting.
Shortly after, the Houston crime lab came under fire for shoddy practices, which led to the retesting of evidence in hundreds of cases.
Court appeals were still pending. There is also still an active civil suit in court, filed by Hughes' lawyer, regarding the use of a single drug for lethal injections.
(Editing by Cynthia Johnston and Eric Beech)