They came for Lemi Ndaki in the night. "I was sleeping when I heard a noise," explains the 70-year-old Tanzanian grandmother. "There was no security in my hut and the door was easy to open. I got up to see about the noise and someone grabbed me and chopped off my arm with a machete. I think he came to chop my neck but I raised my hand and he only took my arm."
A neighbour heard her cries and took her to the hospital in Mwanza, the nearest city, a three-hour drive away on the shore of Lake Victoria. "They couldn't put my arm back on and the scar still hurts, especially when I'm cold." That is not surprising: the open bone still pokes out from the skin below her elbow, 19 years later.
Other elderly women in her village, Mwamagigisi, haven't been so lucky. Ng'wana Budodi was shot in the head with an arrow. Kabula Lubambe and Helena Mabula were knifed to death. Ng'wana Ng'ombe was also murdered with a machete, and when her mud hut was set alight, her husband, Sami, was burnt alive.
This is the fate awaiting thousands of old people, mostly women, who are accused of witchcraft in this rural and isolated corner of east Africa. The killings are escalating in many areas, perhaps numbering more than 1,000 a year, but the Tanzanian government and police do nothing to stop them.
Although belief in witchcraft is common across much of sub-Saharan Africa, relatively few people persecute suspected sorcerers. What exists in the regions of Mwanza, Shinyanga and Tabora - predominantly Sukuma by tribe - is a localised hysteria reminiscent of the witch burnings and trials-by-ordeal of Salem or medieval Europe.
A combination of poverty, ignorance and personal jealousies leaves fearful and frustrated peasants quick to blame any adverse act of fate - a dead child, a failed crop, an inheritance settlement where a sibling receives all the land - on witchcraft. Throw into the pot malicious gossip and an often fatal bout of finger-pointing at old women, and the result is vigilante groups of professional killers moving from village to village, accepting payments to remove the "problem" by hacking, beating or burning. Four cows or $100 is said to be the going rate.
Sometimes local outrage is such that mob rule breaks out and the "witch" is openly lynched. One of the most surprising aspects is the attacks often originate from the victim's family.
"We are talking big numbers as not all cases are reported," said Simeon Mesaki, a sociologist at the University of Dar es Salaam who specialises in witch killings. "They appear to be increasing in some areas. In Shinyanga region you are talking a minimum 300 a year that we know about. Mwanza is probably the same. About 80 per cent of reported attacks are against elderly women."
In 2003 the Tanzanian government said more than 3,072 witch killings had occurred since 1970 - but a government commission said in 1989 that 3,693 had been reported to police between 1970 and 1984 alone. A regional police chief admitted they were a daily occurrence, and a leaked survey by the ministry of home affairs said 5,000 people had been lynched between 1994 and 1998. The problem is so prevalent that villages have been set up populated exclusively by accused witches forced to flee their communities. "The government figures are very low, not accurate," said one official who asked not to be named. "I know a much higher number, and even that is not the full situation."
The root cause of the killings is that village life is so hard, prompting neighbours and relatives into competition over resources that can spill into violence behind the smokescreen of witch hunts.
These are the most deprived parts of a country whose people have an annual income of $330 and a life expectancy of 46 years. There is no electricity or running water; home is a mud hut with a straw roof. Few roads are passable during the wet seasons and 60 per cent of villagers lack adequate sanitation facilities. Rainfall is low and unreliable so crops struggle. Lions and leopards from the nearby Serengeti attack cattle or people.
These conditions result in poor employment, literacy and general health, and susceptibility to superstition. The incidence of HIV/Aids - a mystery to some locals - is thought to be much higher than the countrywide average of one in 10 adults and is decimating the working 18-49 generation. Malaria, typhoid, polio and dysentery kill many more under-fives than the national mortality rate of 165 deaths per 1,000 children.
But life has always been hard here and witch killings were sporadic until the late 1960s. What prompted the explosion in murders was the breakdown of the traditional tribal system of governance. The collectivisation policies of Tanzania's popular first President, Julius Nyerere, tried to bring together 120 tribes through a common language, Swahili. The dialect policy proved successful: despite Tanzania's diversity, it is one of Africa's most harmonious societies.
The second policy, Ujamaa, proved disastrous. It demanded socialist farming collectives, bringing together distant peasants for work and access to basic facilities (many are still waiting for these). Ujamaa's idealism was suffocated by the lack of individual incentive and sowed a more murderous seed by disbanding the system of village chiefs, outlawed in 1963 and replaced by faraway officials.
The chiefs had been responsible for resolving local conflicts - not always amicably, but firmly. Into the authority vacuum stepped the unsung culprits of the witch killings that would tear apart rural harmony: traditional healers, or, as we would crudely recognise them, witch doctors.
This motley crew of diviners (fortune tellers), rain makers, herbalists, bone sitters and traditional birth attendants accumulated great power over their clients. Many enjoyed good reputations for patient care even if their scientific knowledge was poor. But a new generation of hoaxers has set up shop in villages and by highways to prey on passing motorists and pedestrians worried about their fate. These "briefcase specialists", as some locals laughingly call them, attribute undiagnosed illnesses to witchcraft, and - for a price - direct their vengeful clients to the accused sorcerer. Hence the rise in witch killings.
It is the elderly, particularly those whose families have died and so have no protection, who bare the brunt of people's frustrations and anger. Diviners spread money-spinning stories that an individual keeps hyenas and tames snakes, digs up corpses and eats the flesh, and stays up all night bewitching people - hence her bad temper, grey hair and the bags under her bloodshot eyes (actually the result of years toiling over cow dung cooking fires).
A law was passed two years ago obliging the ministry of health to set up a traditional healers' union with a code of conduct for members, but the effect has yet to be noticed.
In Mwamagigisi, the nfumu (diviner), Gamawishi Shija, said people needed to know if they had been bewitched by a neighbour so they could "stop the problem". The 44-year-old Maasai said: "When you have a disease which is unknown you can see it is witchcraft. Ancestors tell me who the witch is when I sleep. Then I tell the patient. When the person dies, [relatives] want to kill the witch. It is for security."
She breaks away from her explanation to tend to a client. The ceremonial importance of handing over money is immediately apparent. Once a coin is tossed in her basket, the diviner sets off on a 10-minute, eyes-closed medley of bell-ringing, whistling and shaking a maraca - to contact the ancestors. Her chants grow louder to drown out the sound of a patient's cough in a hut behind her. Once finished, she returns to her client: "Maybe you are suffering with your backbone, your legs?" With no easy access to dispensaries and medical advice, this is a common experience for rural Tanzanians.
The witch killings are not a problem eroded by the dribble of modernity - radios, mobile phones and cars - into villages. If anything, peasants' growing awareness of their poverty compared to the rest of the country only exacerbates tensions.
The day we passed through Magu town, Mwanza, on the way to the countryside, a old woman was murdered in nearby Busami village after relatives accused her of bewitching her terminally ill husband to an early grave.
Many murders go unreported because villagers cover up the killings to avoid police attention. If the police do receive a report, they arrive a day or two after the attack, once a 4x4 vehicle can be found to negotiate the country trails. By then the killers have fled and there is no evidence.
The best officers can do is round up the victim's neighbours and question them until they buy their way out of jail. Regardless of corruption, law enforcement officials lack the resources to solve the crime and prosecute the perpetrators.
"The government is condoning the killing," said Scolastica Jullu, the executive director of the Women's Legal Aid Centre in Dar es Salaam. "Except for cases of rape of older women, I don't find anyone taken to court. If it was a man or young woman who was killed, the police would investigate, but because it is old women they don't worry."
The government says with so few resources it can do little more than encourage NGOs interested in the problem. "This is an evil, repugnant practice", the district commissioner for Magu, Elias Maaragu, said. "But if old people have no children to protect them, it is not like it is in the UK where you house them together and give them an allowance."
Stepping into this void is a handful of NGOs targeting trouble spots with educational programmes. One charity, Maperece, is recognised as having had particular success in Magu. It gets £20,000 a year from British donors through Help the Aged's Adopt a Grandparent scheme, allowing its 12 volunteers to support elderly people in 58 villages. But such charities are the only agents likely to intervene. Until the Tanzanian government can be embarrassed into action, and until it controls less pitifully empty coffers, that will remain the case.