(CNN) "I did not kill! I did not kill!" a woman shrieks as Saudi police wrap her head with a black scarf.
"Praise God," a Saudi executioner dressed in white tells her.
He lifts his long silver sword and strikes her neck -- a gasp, then she falls silent.
Twice more the hangman hacks at her neck, before stepping away to carefully wipe the blade.
Ambulance workers immediately start placing the woman's remains on a stretcher as charges against her are hurriedly read out over a loud speaker in the Muslim holy city of Mecca.
She was accused of raping her seven-year-old stepdaughter with a broomstick and beating her to death. "A royal decree was issued to carry out the sharia law, in accordance with what is right," the statement says.
Cell phone footage of the execution, leaked last week by activists, gives a rare glimpse into what human rights groups call a barbaric practice of public decapitation as a punitive measure handed down by Saudi Arabia's judicial system. The country executed 87 people in 2014, most by beheading, Human Rights Watch told CNN.
Saudi officials told CNN the punishment is an integral part of their system of Islamic law, and the only violation that took place at the macabre scene was the illegal filming of the act.
The man responsible for the recording now faces charges of violating the country's cyber laws and will be tried, a Saudi official not authorized to speak on the case said.
"We emphasize respect for the right to life as one of the fundamental rights guaranteed by the law. It should not make us forget the rights of other parties violated by the perpetrators, which has to be seen with the same degree of respect, Mohammed al-Muadi, of the government backed Saudi Human Rights Commission told CNN when asked specifically about the practice of beheading.
The oil-rich kingdom appears unyielding to international pressure, but domestically, a quiet debate is ongoing between hardline conservatives and more moderate members of the legal community, experts tell CNN.
Abdulaziz Algasim, a former sharia law judge, said: "From a pure Islamic law point of view there is no limitation for developing capital punishment." But he said that methods such as lethal injection may be considered in coming years. "There is dialogue in the jurisprudence society that another alternative action can achieve the goal with more mercy, and fit better with human rights."
A project inaugurated by the ruling King Abdullah to put laws into writing has ushered in a shift from the current uncodified system, which provides judges with little guideline or precedence.
"This is all part of big issue of division. The sharia court led by conservatives wants to keep the regulation away from the influence of the political regime, so they are very sensitive," Algasim says, "On the other side, the modernization has to be achieved and it needs a lot of development in the public policy if you want to develop a way to measure punishment and establish a more humanized alternative."