A 37-year-old woman has been arrested in Brazil for allegedly killing a teenage girl who was eight months pregnant – and cutting out her baby.

Military police confirmed the suspect, from Uberlândia in the Minas Gerais Triangle, confessed to luring the young woman into her home, doping her and using a stiletto knife to slice her open.

The suspect, from the Monte Hebron neighborhood of Uberlândia, has been named as Aline Roberta Fagundes, reported Tudoemdia.

The victim, 18-year-old Gabrielle Barcelos Silva, went to the home of the other woman – her mother’s neighbor – after she offered to give her second-hand baby clothes, Globo reports. The young woman was offered coffee and juice, both of which were laced with high doses of tranquilizers. The expectant mother was then suffocated and cut open.

The victim’s body was discovered wrapped in a mattress in the yard by the suspect’s son. Police said at the same time they were notified of a woman turning up with a newborn baby at the Clinical Hospital of the Federal University of Uberlândia (HC-UFU), claiming she had just given birth.

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Under police questioning, she confessed to the killing, admitting that she began watching the victim and researching how to perform a C-section after she had herself suffered a miscarriage.

She said her partner had threatened to end their relationship after she miscarried twins a few months ago, so she told him she was still pregnant with just one baby and devised a plan to obtain a child.

However, the woman subsequently claimed her partner knew of the whole plan and helped to hide the victim’s body. He denies any involvement in the crime. Police said the woman sent a message to him saying she was in labor, after committing the crime.

The couple are being questioned by Uberlândia police. According to police the woman will remain in pre-trial detention, but the man's situation will be evaluated later today. A press conference is scheduled to take place this afternoon, Globo reported.

The baby is said to be in a stable condition and under 'special care' in hospital.