Whenever major events such as initiation ceremonies or elections approach in Mali, some children, women and albinos start to become afraid.
Because this is when people - usually from these three groups - disappear.
If their bodies are found, they are rarely intact, as some of their organs have been cut out, to be used in human sacrifices, many people believe.
During May's local elections, the body of seven-year-old Souleymane Camara was found in a bag in a river several days after he had gone missing.
His genitals, heart and liver had been removed.
Many point the finger at politicians, businessmen or anyone seeking their fame and fortune, who believe that the powers of a magic charm will be boosted with a human ingredient.
Those responsible for these crimes are rarely brought to justice.
'Witches'
Mali is one of the world's poorest countries and sociologist Assata Diallo says this provides the perfect conditions for conmen to flourish.
"Charlatans, witchdoctors and other who live by selling dreams can easily attract people by saying they have the solutions to their problems," she says.n
"The get-rich quick society and the difficulty of finding enough food for the whole family make the conmen very imaginative."
Belief in witchcraft is so widespread that there is even a monthly newspaper which specialises in such stories - Kabako.
State prosecutor Fodie Toure says that many healers, and witchdoctors, are coming to cities such as Bamako from the countryside in search of money and new clients.
"We are getting more cases of everything from people being killed for their organs, to graves being dug up and the bones being stolen, so they can be sold - either in Mali or exported," he says.
'Straight to hell'
Mali has strict laws against human sacrifice and anyone found guilty faces the death penalty.
But traditional healers operate openly, prescribing traditional plants or less harmful ways of bringing good luck and many Malians use them before consulting western doctors.
There is even a market for the ingredients used in magic charms in the heart of the capital, Bamako, between parliament and the main mosque.
Here, you can find all sorts of plants and wild animals, alive or dead.
Abdoul Dembele has several examples on display in his stall.
"A lion's head makes you strong, while Arabs often buy hyena heads to become rich and if you know how to use them, cowry shells can bring lots of money," he says.
Malians use the healers for a variety of problems - to seek everything from cures for their ailments, to become rich, or find a husband or wife, or to bring success to their favourite football team.
'Final step'
When I met Abdramane Konate, he was reading cowry shells for a woman who wanted to know if her son would get a visa to go to France.
"Any charlatan or healer who says he can solve someone's problems by spilling human blood will go straight to hell," he says.
Traditional healer Abdramane Konate, with a client
A traditional healer reads the cowry shells to find out if this woman's son will get a visa for France
"Plants and natural herbs have all sorts of medicinal properties. Or if you want to be blessed by God, you can sacrifice a cow, a sheep, or a chicken. But never a human being," he says.
But one of Bamako's best known traditional healers, who wished to remain anonymous, says: "Human sacrifice is a myth for intellectuals, but a reality for us in the business.
"Most people who say they are devout Muslims or Christians are our best customers.
"Human sacrifice is the final step of a process, which only a few can achieve.
"Before the colonial era, the real masters used to practise. Now, there are only trainee witches left."
When I went to ask Police Sergeant Sadio Coulibaly about the scale of the problem, the first thing he said was:
"Just before you arrived, we had a young boy and a girl, who wanted us to arrest their parents, saying they were witches and wanted to eat them.
"We get those kind of cases every week but we rarely get any convictions because of a lack of evidence."
But Sergeant Coulibaly says he personally does not believe in witchcraft.
"Those who kill and mutilate people are mentally disturbed. They need help."