Standing before the Inquisition in Lisbon, Portugal in 1556, Mónica Fernandes, a woman from the coast of modern-day Ghana, was accused of casting malevolent spells and making pacts with demons. Her crime? Seeking a traditional Akan remedy for a simple cat bite.The Portuguese Inquisition was a powerful institution tasked with identifying, investigating and punishing any belief or practice that deviated from official Catholic doctrine. The Inquisition was established in 1536 during the expansion of the Portuguese empire, one of the world’s first global maritime powers. Fernandes’ trial, recorded in meticulous detail by the Inquisitor, Jerónimo de Azambuja, offers a rare and powerful window into a 16th-century clash of cultures. It reveals how a colonial power systematically misunderstood and criminalised local customs, rebranding Indigenous knowledge as dangerous sorcery.As a historian, I spend my time searching for connections between people across the early modern world, especially the lives of women and children within the vast Portuguese empire. While I was researching the trials of Indigenous women in colonial Brazil, a question began to form: were women in other parts of the empire, like west Africa, also being targeted for their traditional knowledge? This question led me to the archives of the Portuguese Inquisition and to a remarkable case file from 1556. Read more: Colonial powers tried to stifle traditional healing in Zimbabwe. They failed and today it's a powerful force for treating mental illness The file detailed the trial of Mónica Fernandes, an Akan woman from what’s now Ghana. Her story opens a rare window onto the personal, human impact of colonisation. It shows how a vast imperial power operated on the ground: by misunderstanding, criminalising, and attempting to erase Indigenous ways of knowing. Recovering stories like this helps us understand a legacy of cultural suppression that continues to resonate today. A life between two worldsMónica was born to Akan parents. The Akan are a collection of related peoples, primarily living in modern-day Ghana and Côte d'Ivoire. Organised into matrilineal states, they had established sophisticated societies with rich cultural, religious and social knowledge systems long before the arrival of Europeans. The Portuguese first arrived on the west African coast in the late 15th century, driven by a desire for gold. They established their authority by constructing fortified trading posts like São Jorge da Mina (now Elmina Castle) that imposed their laws and religion on the surrounding communities.Mónica lived and worked in and around São Jorge da Mina, a place of intense cultural collision. Baptised into the Catholic faith, she existed between two worlds: the rigid, hierarchical society of the European fortress and the vibrant Akan village of Edina that surrounded it.Like others, she moved between these spaces to socialise, shop and, crucially, seek medical care. It was this last activity that brought her to the attention of the Inquisition. Instead of visiting the Portuguese apothecary at the fortress, Mónica consulted a local Akan healer, an ɔkɔmfoɔ or odunsinni, to treat a cat bite. She procured an ointment, a common practice she saw as rudimentary healthcare.To the Inquisitor, however, this was proof of heterodoxy, or a belief, opinion, or practice that went against the officially established doctrines of Catholicism. Mónica’s choice to trust her community’s medical expertise over that of the Portuguese was seen not just as a rejection of European authority, but as evidence of a pact with the devil. Custom vs. crimeThe accusations against Mónica were dramatic and personal. The initial charge stemmed from a quarrel with another African woman, Ana Fernandes, who was visiting São Jorge da Mina from Lisbon. Witnesses claimed that after an argument, Mónica cast a spell on Ana. Weeks later, after returning to Portugal, Ana succumbed to a mysterious illness that allegedly caused the skin to peel from her face. This rumour, spread by a single witness, became the centrepiece of the case.The rumour of Mónica’s curse spread, prompting a formal inquiry by the Portuguese captain at São Jorge da Mina. It was only after this local investigation, which took months, that Mónica was officially detained and transported as a prisoner to face the main tribunal in Lisbon. The Inquisitor’s interest went beyond this single event, expanding to include other, more everyday practices. Witnesses interviewed at São Jorge da Mina also claimed Mónica conducted spells using chickens and yams. While these details were recorded as evidence of sinister rituals, they were in fact staple elements of Akan cultural life. Yams, a starchy, edible tuber, similar to a potato, were a vital food source and central to ceremonies honouring ancestors, while animal sacrifice was a common preparation for deities.What the Portuguese Inquisitor labelled feitiços (witchcraft or charms) was, for Mónica and her community, simply aduro (medicine) and amammerɛ (custom). The trial documents painstakingly list her heterodoxical activities, but in doing so, they inadvertently preserve a record of the very cultural knowledge the Inquisition sought to destroy. Mónica’s case becomes a catalogue of everyday Akan practices, seen through a distorted colonial lens.A defiant accusedThroughout months of imprisonment and interrogation, Mónica was pressed to confess to witchcraft. She consistently refused. In Akan culture, the concept of bayie is sometimes translated as “witchcraft”, but it specifically refers to acts of acute spiritual wickedness or illness. Mónica’s actions did not fit this category. She was treating a physical ailment, a cat bite.Mónica’s refusal to accept the label of “witch” was therefore not simple denial. Her defence was based on a clear cultural distinction, one she clung to despite her limited Portuguese. When she insisted that she had committed no crime because “all the black men and women of Mina did it too”, she was not admitting to collective guilt. She was trying to explain that her actions were customary medicine, not malevolent spiritual work. She understood the difference between her own system of knowledge and the crime of which she was accused, and she refused to conflate them.The verdict and legacyUltimately, Mónica was found guilty of witchcraft, but the Inquisitors deemed her actions “minor”. She was given the light sentence of a period of religious re-education in Lisbon to study Christian doctrine. Mónica secured her release by demonstrating good Christian behaviour, but was forbidden from returning to her homeland.Mónica’s light sentence was relatively uncommon but unlikely to have been the first instance of re-education. It is possible that women from other Portuguese colonial territories also suffered similar fates, but many records have been lost due to the Lisbon Earthquake (1755) and the deliberate destruction of the Goa Inquisition cases which also took in east Africa. We don’t know what happened to her after her release. But her story, buried in the archives for over 450 years, remains deeply relevant. It is a powerful, personal account of how colonialism operated not just through military force, but through displacement and the deliberate suppression of local knowledge. Mónica’s trial is a stark reminder that the branding of Indigenous practices as “magic” or “superstition” was a tool used to assert dominance and erase entire ways of knowing the world.Jessica O'Leary works for Monash University, a partner of The Conversation.