A 38-year-old woman has been arrested in Brazil accused of pretending to be a 12-year-old girl to deceive a couple who took her into their home for more than a year.

Amanda Maria Souza de Oliveira was charged in the southern state of Santa Catarina with fraud and false identity offences.

During the nearly 16 months she lived with the couple in the city of Joinville, she reportedly had all her expenses paid, a bedroom decorated with toys and children’s furnishings, and a party to celebrate her purported 12th birthday.

The case has been widely reported in local media, prompting disbelief that Oliveira allegedly managed to sustain the deception for so long.

After she was arrested just over a week ago, it emerged that Oliveira had previously been charged in several other Brazilian states for allegedly carrying out similar schemes.

The public prosecutor Viviane Soares said the investigation had uncovered “an elaborate fraud scheme involving the creation of a fictitious identity and the emotional manipulation of victims in order to obtain undue advantages”.

The couple told police Oliveira first approached them at an evangelical church they attended, introducing herself as “Gabrielle” and claiming to be 18 years old. She reportedly said she was experiencing financial and health difficulties, prompting the couple to take her in.

She later allegedly changed her story, claiming she was in fact 11 but appeared older because her father had forced her to take hormones and had sexually abused her. She also allegedly persuaded the family not to enrol her in school or formalise any adoption process, arguing that doing so could enable her father to find her.

The alleged deception unravelled after an aunt who occasionally visited the family became suspicious of Oliveira’s age. After searching online, she found reports of a similar case in Rio de Janeiro three years earlier in which Oliveira had allegedly deceived another family.

Videos and photographs shared by other alleged victims show Oliveira using dummies and baby bottles and speaking in a childlike manner.

The earliest known case involving Oliveira dates to the late 2000s in her home state of Ceará. Already in her 20s, she allegedly went to a police station claiming to be 12 years old and a victim of sexual abuse and forced into sex work by her parents.

Rafael Luiz Siewert, Oliveira’s lawyer, said that after interviewing her he had “identified elements that justified requesting a psychiatric evaluation”.

The judge granted the request and proceedings have been suspended until it is established whether Oliveira is fit to stand trial. In the meantime, she remains in prison.