Huge development in police case against alleged killer mushroom cook Erin Patterson

Deadly mushroom chef Erin Patterson's internet search history and deleted social media accounts will reportedly form a vital part of the prosecutor's case against the accused killer. 

The mother-of-two, 49, was arrested at her home in Leongatha, eastern Victoria, and charged with three counts of murder and five counts of attempted murder on November 2.  

Her former in-laws, Don and Gail Patterson, both 70, and Gail's sister Heather Wilkinson, 66, all died within days of eating an allegedly poisonous beef Wellington lunch at Patterson's Leongatha home on July 29.

Heather's husband, Baptist church pastor Ian Wilkinson, 68, narrowly avoided the same fate, while Patterson's husband Simon pulled out at the last minute.

She is accused of attempting to murder him three times.

Erin Patterson (pictured), 49, was arrested at her home in Leongatha, eastern Victoria, and charged with three counts of murder and five counts of attempted murder on November 2

In February, new details emerged about the items found by technology detector dogs in Patterson's home

READ MORE: What police dogs found inside the home of murder accused mushroom chef Erin Patterson 

The dogs were seen exploring various locations at the home, including a rear deck

Detectives are particularly interested in Patterson's Facebook usage, according to the Herald Sun.

The paper was told Patterson allegedly created various profiles under different names.

Daily Mail Australia previously revealed that Patterson once allegedly boasted on Facebook that she was 'very good at details', while deriding the writing ability of some people in her local community.

Patterson branded contributors to Korumburra newsletter The Burra Flyer 'illiterate motherf**kers' during a rant to an old friend.

She and her then husband Simon had put together the 48-page booklet of advertorials and promotions of the regional Victorian community for years after taking it over from Simon's parents.

In another message, Erin seemingly took aim at Simon himself, attacking the engineer for failing to do enough housework. 

'My husband has no idea we have a cleaner come. I love it,' Erin allegedly posted while the couple were still together. 

'Now I don't resent the fact that he never helps me with anything because I'm not doing the big jobs either... now all I have to resent him over are the nightly dishes.'   

Police are also looking at her internet history, with specialist teams able to unearth deleted searches. 

'It’s not easy but it’s doable on most occasions,' a police source told the paper.

'She might be involved in conversations or narratives where she has talked about this stuff on online forums ... it could be the tiniest thing.'

Daily Mail Australia previously revealed that Patterson once allegedly boasted on Facebook that she was 'very good at details' , while deriding the writing ability of some people in her local community (pictured) 

Technology detector dogs discovered several items of interest, including a mobile phone, five iPads, a trail camera, and secure digital card and a smart watch

In February, new details emerged about the items found by technology detector dogs in Patterson's home. 

One of the dogs, Georgia, found a USB, a micro secure digital card and a SIM card, a Senate estimates hearing was told. 

'Technology Detector Dog Alma found a mobile phone, five iPads, a trail camera, and secure digital card and a smart watch,' AFP Commissioner Reece Kershaw said.

'These were not found during initial searches undertaken by officers.' 

Pastor Ian Wilkinson was the only one to survive the deadly lunch, which claimed the life of his wife Heather Wilkinson, 66. He spent almost two months in hospital (the pair are pictured together)

Gail Patterson and brother-in-law Don Patterson, both 70, also perished following the lunch

The canines are considered to be the most elite of all sniffer dogs due to their ability to sense the microns-thin coating that protects computer circuit boards. 

The AFP said their noses are so sensitive they can even find tiny SIM or memory cards buried in walls or hidden in fruit. 

Patterson is currently behind bars in Victoria's largest women's prison, the notorious Dame Phyllis Frost Centre in Melbourne's western industrial suburbs. 

She is next due in court on April 22.

READ MORE: Accused mushroom lunch chef Erin Patterson lists her $1million 'holiday home' up for sale

Patterson's two-storey townhouse in Mount Waverley, in Melbourne's south-east, was placed on the market on October 27, six days before her arrest