Hundreds of bystanders, including many children, watched and some took photographs of Wednesday's brutal slaying. Grisly pictures were published on the front pages of the country's biggest circulating newspapers, The National and Post-Courier, while the prime minister, police and diplomats condemned the killing.
In rural Papua New Guinea, witchcraft is often blamed for unexplained misfortunes. Sorcery has traditionally been countered by sorcery, but responses to sorcery allegations have become increasingly violent in recent years.
The death was the first sorcery-related murder in Papua New Guinea in a year, national police spokesman Dominic Kakas said.
Kepari Leniata, a 20-year-old mother, had been accused of sorcery by relatives of a 6-year-old boy who died in the hospital the day before.
She was tortured with a hot iron rod, bound, doused in gasoline, then set alight on a pile of car tires and trash in the Western Highlands provincial capital of Mount Hagen, Kakas said.
Deputy Police Commissioner Simon Kauba on Friday blasted Mount Hagen investigators by phone for failing to make a single arrest, Kakas said.
The public were apparently not cooperating with police and police carrying out the investigation were not working hard enough, Kakas said.
"He was very, very disappointed that there's been no arrest made as yet," Kakas said.
"The incident happened in broad daylight in front of hundreds of eyewitnesses and yet we haven't picked up any suspects yet. He was very, very curious about that and he blasted the investigators on the phone," Kakas added.
Kakas described the victim's husband as the "prime suspect" and said the man fled the province. Kakas said he did not know if there were a relationship between the husband and the dead boy's family.
He said more than 50 men and people are suspected to have "laid a hand on the victim" and committed crimes in the mob attack. While many children had witnessed the murder, there were no child suspects, he said.
Police Commissioner Tom Kulunga described the murder as "shocking and devilish."
"We are in the 21st century and this is totally unacceptable," Commissioner Kulunga said in a statement.
He suggested courts be established to deal with sorcery allegations, as an alternative to villagers dispensing justice.
Prime Minister Pete O'Neill said he had instructed police to use all available manpower to bring the killers to justice.
"It is reprehensible that women, the old and the weak in our society should be targeted for alleged sorcery or wrongs that they actually have nothing to do with," O'Neill said.
The U.S. Embassy in the national capital Port Moresby issued a statement calling for a sustained international partnership to enhance anti-gender-based violence laws throughout the Pacific.
The embassy of Australia, Papua New Guinea's colonial ruler until independence in 1975 and now its biggest foreign aid donor, said "We join ... all reasonable Papua New Guineans in looking forward to the perpetrators being brought to justice."