Homicide detectives are probing the deaths of three people from suspected mushroom poisoning.
Four people were taken to hospital a day after eating at a home in Leongatha, in Victoria's South Gippsland area.
Two Korumburra women, aged 66 and 70, died in hospital on 4 August.
A third person, a 70-year-old Korumburra man, died in hospital on Saturday night.
A 68-year-old Korumburra man remains in hospital in a critical condition.
Investigators executed a search warrant at a home in Leongatha on Saturday.
They also questioned a 48-year-old Leongatha woman who was released pending further enquiries.
Police are liaising with the Department of Health in relation to the matter.
