Texas is tonight set to execute a man found guilty of murdering his wife and two stepsons in a frenzied knife attack and raping his two stepdaughters.
Robert Sparks, 45, will be put to death by lethal injection for the September 2007 attack in which he stabbed his wife Chare Agnew 18 times as she slept in their bed.
He claimed he thought his 30-year-old spouse had been poisoning him.
After killing her, he woke up the boys - Harold Sublet Jnr, nine, and Raekwon Agnew, 10 - and took them separately into the kitchen, where he knifed them them 45 times each.
Sparks proceeded to wake up his two stepdaughters, LaKenya Agnew, 14, and Garysha Brown, 12.
He tied them up and sexually assaulted them.
He then told the girls that their mother tried to poison him, according to court documents.
Sparks locked his stepdaughters in a closet and left the home, stopping at his mother's house to borrow her car, and then his ex-girlfriend's home, where he told her he had killed his wife and two stepsons.
He then called police and confessed, court records showed.
After traveling to Austin for a few days, Sparks returned to Dallas and was arrested. He told police his wife had been poisoning him.
He provided blood, hair and fingernail samples, as well as a cheek swab, to be tested for evidence of poisoning, but investigators were unable to find a lab capable of that type of test, according to court papers.
Sparks - diagnosed as psychotic with delusions and with schizoaffective disorder, according to court documents - claimed a voice in his head told him to kill his wife and stepsons.
Barring a last-minute stay, he is due to be executed at the state prison in Huntsville at 6pm local time on Wednesday.
He claims he is intellectually disabled and therefore is not eligible for the death penalty.
He has argued that an expert for the prosecutor gave false testimony and a courtroom bailiff may have tainted the jury's death penalty decision by wearing a homemade tie depicting a syringe to show his support for the death penalty.
Sparks is set to become the 16th inmate - all men - in the US and the seventh in Texas to be executed this year.
Texas has executed more prisoners than any other state since the Supreme Court reinstated the death penalty in 1976.
