Updated

Convicted killer Preston Hughes III was executed Thursday for the fatal stabbing of a 3-year-old boy and the child's teenage cousin who uttered her attacker's first name to police in her dying breaths 24 years ago in Houston.

Hughes, 46, insisted he was innocent, contending police planted evidence and coerced his confessions to the September 1988 slayings of Shandra Charles, 15, and her cousin Marcell Taylor.

He was pronounced dead at 7:52 p.m. CST.

Hughes became the 15th Texas prisoner executed this year and the second in as many nights. On Wednesday, Ramon Hernandez, 41, was executed for the abduction and murder of a San Antonio woman.

Charles and her young cousin were attacked in a field behind an apartment complex where Hughes lived. A man walking along a trail found Charles and called police.

Officers found the 3-year-old already dead from a stab wound that passed completely through his neck. Charles was still alive but severely injured with knife wounds to her neck and chest, police said. When an officer asked who was responsible for the attack, she gave a name, "Preston," and said he tried to rape her. She died moments later.

Authorities went to the nearby apartments and found Hughes, the only resident with the first name of Preston. He already was on probation for a conviction of sexual assault on a child and denied any role in the attacks.

The punishment came after Hughes lost multiple appeals and lawsuits in courts to block it. Two appeals -- filed by attorney Patrick McCann, who Hughes unsuccessfully sought to fire -- failed at the U.S. Supreme Court.

Other court actions were filed on Hughes' behalf by a death penalty opponent in Houston. They were denied in the courts or could not halt the punishment, attorneys said.

In one Supreme Court appeal, McCann said instructions to jurors deciding Hughes' punishment were not adequate. Hughes, however, was "properly convicted and sentenced to death," Jefferson Clendenin, an assistant Texas attorney general, told the justices.

In another high court action, McCann contended new evidence showed Hughes was sexually abused as a child and a jury should be allowed to consider that at a new punishment trial. He also obtained an affidavit from a former medical examiner who questioned whether Charles, after massive blood loss from her stab wounds, could have still been conscious or even alive by the time police arrived to ask her about her attacker.

State attorneys argued the assertions from McCann were "patently meritless and nothing more than a last-minute Hail Mary," said Fredericka Sargent, an assistant attorney general.

Additional appeals focused on the legality of using a single lethal dose of pentobarbital for executions, a procedure Texas adopted earlier this year.

Another, from Hughes, accused the Texas Board of Pardons and Paroles of violating his rights when they declined a clemency request filed by his lawyer but refused to consider a similar request from activist Ward Larkin. And another raised civil rights violations in a lawsuit against the mayor of Houston, alleging improprieties and fraud in the Houston police crime lab that handled evidence in Hughes' case.

Ellis McCullough, one of Hughes' trial lawyers, said this week he was convinced no evidence was planted or mishandled.

He said Hughes, brought to a police station for interviews in the early morning hours after the slayings, made phone calls from the police interrogation room to acquaintances, including his probation officer, that "were pretty devastating taken as a whole."

"He didn't help himself any," McCullough said. "It was pretty convincing he was the guy."

Evidence examined for DNA testing after his conviction and at his request found traces of Charles' blood on Hughes' clothing. At his trial, prosecutors showed Charles' glasses were found on a couch in his apartment. Hughes, who knew Charles through a friend, said police took the evidence from the crime scene, planted it in his apartment, illegally searched the place, coerced his confessions and copied his signature to them from another document.

"The fact is I didn't kill anyone," he told The Associated Press last month, speaking from a small visiting cage outside death row.

Hughes also denied the sexual assault conviction that resulted in his probation.

"I didn't know she was 13 at the time," he told the AP of the victim in that case. "I was led to believe she was 17."

Hughes moved to Houston in 1983 from his native Buffalo, N.Y., where a rape charge against him was dismissed when the victim failed to appear in court.

He testified at his capital murder trial that he pulled a knife on "a guy who came up to me from behind" and "stuck him twice" but denied it was Charles or the 3-year-old.

"I didn't stab anybody," he said. "Stabbing and stuck is two different things."