Texas carries out execution of oldest death row inmate as Melissa Lucio continues to fight for freedom

The execution was the first in which an inmate’s religious adviser was allowed to be present to pray

Texas has executed its oldest death row inmate by way of lethal injection.

Carl Wayne Buntion, 78, was put to death just before 6.40pm on Thursday, according to the Texas Department of Criminal Justice.

Buntion, the first inmate executed in the state this year, was put on death row after he was convicted of fatally shooting a 37-year-old Houston police motorcycle officer, James Irby, after a 1990 traffic stop.

During the fatal stop, Buntion shot the 19-year police veteran in the head and shot him twice more in the back once he fell to the ground.

According to state documents, Buntion was eventually captured inside a nearby warehouse after shooting at three other people, including two witnesses, while he was fleeing on foot.

The execution was notable as being the first in which an inmate's spiritual adviser was allowed to be present and to touch and pray during the execution.

Meanwhile, Melissa Lucio, a Texas mother convicted of killing her two-year-old child, is still fighting to have her execution stayed.

She and her supporters claim her confession was coerced by investigators. It was central to the prosecutor's argument during her murder trial.

Mounting evidence – much of which was not heard at her trial – suggests that her child's death was caused by an accidental fall, and not the result of Lucio's actions.

Lucio's execution is scheduled for 27 April, but her supporters are calling for a stay and a review of the evidence that landed her in prison in the first place.

Those supporters include Kim Kardashian – who has advocated for other death row inmates who were convicted on questionable evidence – as well as hundreds of religious groups and women's and domestic violence advocacy organisations.

Five of the jurors who initially convicted Lucio have also called for a reprieve after reviewing the evidence that was not presented in court.

At the time of her questioning, Lucio's children told investigators that she had never been abusive or violent in any way. They also told investigators that they had seen their sibling – the two-year-old who died – acting listless and sleeping for long hours prior to her death. Those symptoms are consistent with a brain injury caused by a fall.

The child, Mariah, also had a medical history of difficulty walking and had suffered falls in the past.

Mariah died after falling down the stairs. Lucio called 911, but paramedics were unable to safe the child after she stopped breathing.