(NBCNews) — A small family lunch in a quiet Australian town is now at the center of a possible murder mystery, thanks to wild mushrooms that were apparently on the menu for everyone except the hosts.

A homicide investigation has been launched after three guests died and a fourth became critically ill in the days after the meal, all with symptoms that police say were consistent with death cap mushroom poisoning.

Police have interviewed the 48-year-old woman who cooked and hosted the meal for her in-laws and another couple on July 29. She was released without charges pending further inquiries, but her residence has been searched and some items have been removed for testing, Victoria police said in a statement.

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