A daughter-in-law cooked the suspected poisonous mushroom meal that killed three people and has put a church pastor in hospital fighting for life.
Homicide squad detectives are investigating after guests at a family lunch at Leongatha in Victoria's east fell ill on July 29.
Four people went to local hospitals the following day and were transferred to Dandenong Hospital and Austin Hospital.
A 66-year-old woman from nearby Korumburra died in care on Friday and her 68-year-old husband - a Baptist Church pastor - remained in a critical condition at Austin Hospital on Monday afternoon.
The woman's 70-year-old sister and brother-in-law, also from Korumburra, died in hospital on Friday and Saturday.
Investigators interviewed the 48-year-old daughter-in-law of one of the couples who cooked the meal at her home.
She did not become ill.
No charges have been laid but police are still treating her as a suspect.
Outside her Leongatha home on Monday afternoon, the woman said she did not know what had happened.
"I didn't do anything," she told Nine's A Current Affair.
"I loved them and I'm devastated they're gone."
She declined to answer questions about what meals were served to which guests or the origin of the mushrooms.
Detective Inspector Dean Thomas said the woman was separated from her husband but police have been told their relationship is amicable.
"It could be very innocent but, again, we just don't know at this point," he told reporters on Monday.
Her children were also at the home on July 29 but did not eat the meal.
The Department of Families, Fairness and Housing has taken the children as a precaution.
Detectives searched the home on Saturday and seized multiple items which they declined to detail.
They are yet to confirm the type of mushroom the guests ate but Det Insp Thomas said the symptoms were consistent with those from eating a death cap.
"We're working closely with (the) Department of Health and of course our poisons medical experts," he said.
Det Insp Thomas warned Victorians against eating wild mushrooms.
The families of the dead are grappling with shock and grief.
"Our beloved family members, who we will not name at this time out of respect for their privacy, were cherished individuals," the Patterson and Wilkinson families said in a statement published in the South Gippsland Sentinel Times.
"They were parents, grandparents, siblings, children and pillars of faith within our community.
"Their love, steadfast faith and selfless service have left an indelible mark on our families, the Korumburra Baptist Church, the local community and indeed people around the globe."
South Gippsland mayor Nathan Hersey said the small Korumburra community was in mourning.
Following a service on Sunday, the mayor spoke with the Baptist Church congregation, who have been gathering regularly to pray for the victims.
"It's hard because we've had a lot of people experience a lot of grief all at once," Cr Hersey told AAP.
"It's shock and it's grief and it's sadness and it's not just with one person they love but with three ... they loved dearly who (have) passed away and then now another who's in a critical condition."
Victoria had a spate of death cap mushroom poisonings in 2020, with eight people in hospital at one point.
Five required intensive care and one died.
© AAP 2023