By Phil Mercer
BBC News, Sydney
It is believed the victims were tortured by fellow villagers in a remote highland region 400km (250 miles) north of capital
Police believe they were forced to confess to witchcraft after they were stabbed with hot metal rods.
Human rights campaigners say it is not uncommon in
These four women had been accused by fellow villagers of using sorcery to cause a car crash in which three prison guards died.
A senior police officer said it appeared the killings took place last October and that a tip-off from tribal elders had eventually alerted the authorities.
The women's bodies were found hidden in an old pit.
It is not clear if any charges will be laid.
Superstition has always been part of life in
Death and mysterious illness are sometimes blamed on evil curses and suspected sorcerers are often blamed and then killed.
Researchers have found that the victims are usually elderly women with little influence in the village.
Prosecuting those who kill these so-called magic makers within tight-knit communities is problematic, with potential witnesses often refusing to speak to the police.
Christianity is a powerful force in
Those suffering from HIV and Aids are often seen as the victims of witchcraft.
In the past, some Aids victims have been thrown off bridges or dumped into graves to die.