An elderly South Australian couple, who died more than a year apart, may have been murdered by the same person, with concerns raised over suspicious toxicology reports.
Police say Brenda Anderson, 94, died in the Flinders Medical Centre in March last year.
Her husband Lynton, 94, died after being found unconscious by a carer at his home in May this year.
Detective Inspector Mark McEachern said concerns over Mrs Anderson's death were first raised during the coronial investigation, which unearthed the toxicology results.
"When an innocent explanation for toxicology abnormalities was eliminated, the possibility of Mrs Anderson's death being a deliberate act by another party became the primary subject of the investigation," Insp McEachern said.
"It is believed Mrs Anderson was killed by a person known to her and in close enough relationship to have been visiting her while she was in hospital."
He said police had no concerns about the level of care she received in the hospital, and had ruled out anyone there being involved.
Mr Anderson also died in hospital and a similarly concerning toxicology report was returned.
"Police have eliminated external carers involved with Mr Anderson's care as being involved in his death," Insp McEachern said.
"We have identified a suspect and won't elaborate further."
Detectives would like to speak to anyone who had contact with the couple, particularly anyone with knowledge of any prescription or non-prescription medications they were taking.
