A 70-year-old Australian woman has been charged with murder following a complex, three-year investigation into the death of Isaac Oar, a 56-year-old man with Down Syndrome, who was found deceased in his home weighing just 29 kilograms. Maria Concepceion Arrieta was arrested Tuesday and charged with one count of murder, specifically domestic violence related. She appeared in Brisbane Magistrates Court.
Mr. Oar was pronounced dead on August 10, 2023, at an address in Ayr, a town south of Townsville, Queensland. Queensland Police described the investigation as complex, involving thorough inquiries into Mr. Oar's health, care, and treatment throughout his life. A crime scene was established at the Alice Street address where he was found.
Police released footage last year showing the interior of Mr. Oar's home, which was cluttered with stacked belongings, with room entrances blocked by boxes and objects spilling from containers. Detective Inspector Jason Shepherd stated in 2025 that Mr. Oar was found to be seriously malnourished. He had not received professional medical treatment for over a decade, complicating the investigation. Police believe individuals who had contact with the family or the home in the years leading up to Mr. Oar's death may possess information that could assist their inquiries. Arrieta, Mr. Oar's primary caregiver and older sister, was identified as a person of interest early in the investigation.