Australian police said on Thursday they had arrested a 49-year-old woman over the deaths of three elderly people in August after they allegedly consumed mushrooms at a lunch hosted by her.

Victoria state police said they had searched the woman’s house with the help of technology detector dogs – trained to sniff out tiny electronic devices such as USBs and SIM cards, which are easy to hide. The woman will be interviewed by police and the investigation remained ongoing, Victoria police said in a statement.

Don Patterson, his wife Gail Patterson and her sister Heather Wilkinson, became ill and later died after the lunch on July 29 in Leongatha, a small rural town around 135 km (85 miles) southeast of Melbourne.

A fourth man, Wilkinson’s husband Ian Wilkinson, a pastor in a nearby town was released from hospital in September.

The mysterious deaths have gripped Australia. Deaths from consuming mushrooms are relatively rare in the country, which has several species including the “death cap” mushroom that are dangerous enough to poison and kill a human.