Maria Concepceion Arrieta was arrested on Tuesday following a "complex" investigation into the death of Isaac Oar, a 56-year-old non-verbal man with Down syndrome.
Mr Oar - also known as "Ike" - was discovered unresponsive and declared dead by emergency services who were called out to a north Queensland address on August 10, 2023.
Police appealed for information in January 2025, alleging Mr Oar died after years of neglect.
"Isaac was found seriously malnourished - he was only 29kg at the time of his death," Detective Inspector Jason Shepherd told reporters in early 2025.
"He hadn't been or received any professional medical treatment in well over a decade so it makes the investigation quite complex."
Police shared footage of inside Mr Oar's dwelling in Ayr, south of Townsville, as they investigated his death.
Officers can be seen walking through the dwelling in 2023 cluttered with belongings and entries to some rooms blocked by boxes with objects spilling out of bags and containers.
Police on Tuesday arrested Arrieta, of Forest Lake in Brisbane's south, following a lengthy investigation.
She was charged with one count of murder (domestic violence).
"Investigations into the death of the man have been complex, with detectives conducting extensive and thorough inquiries into (Isaac's) health, care, and treatment throughout his life," police said in a statement on Wednesday.
Arrieta's matter appeared in Brisbane Magistrates Court on Wednesday.
It was adjourned for mention at Townsville Magistrates Court on Friday.
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