The final words of a murderer who killed his wife and two stepsons have been revealed.
Robert Sparks, 45, who raped his two stepdaughters after a stabbing spree, appeared to apologise to his family just before he was executed at 6.39pm local time (CDT).
The US Supreme Court rejected his appeal for a stay of execution just hours before he died by lethal injection for the September 2007 attack.
Sparks stabbed his wife Chare Agnew 18 times as she slept in their bed, claiming he thought the 30-year-old had been poisoning him.
He then knifed his two stepsons to death, before sexually assaulting his stepdaughters.
Speaking from the execution chamber in Huntsville, Texas, he said: "Umm, Pamela can you hear me Stephanie, Hardy, Marcus tell all the family I love them.
"I am sorry for the hard times and what hurts me is that I hurt ya'll too and Patricia she wrote me tell Patricia I wrote her back and to tell ya'll what I said. I love y'all. I am ready."
After killing his wife, Sparks woke up his 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.
He said he was intellectually disabled, with an IQ of 75, and therefore not eligible for the death penalty, the Texas Tribune reports.
The murderer 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 has 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.
