Jurors in Steven Long's capital murder trial deliberated less than an hour Friday before sentencing the convicted child killer to death for the May 2005 sexual assault and strangulation of an 11-year-old Dallas girl.

Mr. Long, 35, showed no reaction as he was led away in shackles after District Judge Keith Dean's parting words: "Mr. Long, may God have mercy on your soul."

Jurors in the two-week trial heard graphic details of Kaitlyn Briana Smith's final moments inside a trailer in the southeast Dallas community of Rylie. In his confession to police, Mr. Long admitted beating and sexually assaulting the girl, then strangling her and dumping her battered body underneath a vacant trailer nearby.

The fifth-grader had been at a sleepover at the mobile home where Mr. Long was also staying as a guest.

Jurors said it didn't take long to agree on the death sentence because they were unanimous in their belief that Mr. Long posed a threat to society even if he were in prison for life.

The panel of eight men and four women also agreed that none of the many hardships in Mr. Long's background warranted that he be given a life sentence instead.

"It was horrific," one sobbing juror said as he left the courtroom.

Lead prosecutor Andy Beach said the level of violence that Mr. Long unleashed on the child made the jury's decision easy.

"Kaitlyn's body was all the evidence they needed," Mr. Beach said. "This is one of those crimes – if you do it, you've crossed the line and you're going to pay."

With so much evidence implicating Mr. Long, defense attorney Paul Johnson said his strategy all along was to fight to save Mr. Long's life.

"What he did to that little girl was unimaginable and inexcusable," he said in closing arguments, adding that the state had not proved that Mr. Long posed a continuing threat to society. He also noted that Mr. Long had been severely neglected as a child.

"This man will never walk our streets again," he said. "Do we really have to kill him? Is he really a threat to society? We can't go out and respond to his barbarism with untempered barbarism."

But Mr. Beach said Mr. Long's history of violence proves that he would continue to be a risk even in prison. During the trial, witnesses testified that Mr. Long had physically abused his pregnant wife, had sexually assaulted a 13-year-old girl when he was 20 and had taken part in a prison riot while serving a sentence for attempted murder.

"A man capable of the atrocities that Steven Long performed that night is capable of doing anything," Mr. Beach said. "This sexually sadistic, chronically angry individual is always going to be a threat no matter where he is."

Kaitlyn's mother and grandmother said they were relieved by the death sentence.

"You are not human at all but a beast always hunting and preying on the weak, small and innocent," Kaitlyn's grandmother, Wanda Holder, told Mr. Long after his sentencing. "I understand that hell is hot for eternity, and that's a long time."