Details emerge about Australian professor found dead in Argentina.

-With AAP

When Lily Pereg stopped replying to her friends in a WhatsApp group she would usually post in daily, those closest to her immediately grew worried.

The NSW university professor, who is described by her family as having a “lust for life”, had been travelling with her sister Pyrhia Sarusi.

She had been keeping her friends updated on her movements when suddenly, she and her sister both vanished without a trace earlier this month.

Numerous messages went unanswered in the group the friends shared, which they admit they found “weird”, but assumed she had become too engrossed in her adventure to respond.

Then two weeks later, they learned the truth.

Both women’s bodies were found buried in a shallow grave – with evidence that one had been shot.

The body of 54-year-old University of New England microbiology professor Lily Pereg, and that of her 63-year-old sister Pyrhia Sarusi, both born in Israel, were discovered on Saturday local time near the city of Mendoza.

The bodies were buried on a lot beside the house of Ms Sarusi’s son Gilad Pereg, 36, according to Argentina prosecutor Claudia Rios.

The home of their alleged murderer.

Pereg was arrested on Friday and formally charged a day later with the aggravated homicide of his mother and the homicide of his aunt.

The family are lost for words at the discovery, making an emotional statement on the GoFundMe page they had started in an effort to raise money for a search of the sisters.

"We the family, are shocked. Gilad Pereg, Pyrhia Sarusi's son, standing accused of murdering his Monther and Aunt [sic]," the women's family said.

"We at the family are at owe and humbled by the outpouring of support and love, worldwide. Your love carried us and will help us recover from a huge tragedy. There will never be an explanation."

The page had generated donations of more than $7500 to go towards the search, funds that will now be donated to charity.

The women had travelled to Mendoza to visit Gilad, who had been living in Argentina for more than 10 years. They vanished around January 11.

Childhood friend Eti Krief Haimi said she was in daily contact with Ms Pereg via a WhatsApp group chat called "friendship forever".

"The last message you sent to us on 11/1/19 hour 23.06 was: "wishing you a peaceful Shabbat.. Shabbat shalom dear girls.." with full of hearts and flowers," she posted on Facebook.

"You stopped responding to us, it was a little weird, but we thought you were on a flight somewhere."

She paid tribute to Ms Pereg's "big smile" and love of life and travel.

"You left a huge hole with us. We didn't dream in the worst deal we'd have to break up with you so fast."

Autopsy results showed at least one of the women was shot. Local media are reporting the victim had suffered three gunshot wounds while the other showed signs of having been dragged.

Gilad Pereg, who reportedly was the Argentine chairman of five companies set up by his mother, has now been transferred to a local prison.

The Department of Foreign Affairs and Trade on Monday confirmed it was providing consular assistance to the family of an Australian woman who died in Argentina.

"Owing to our privacy obligations we will not provide further comment," a spokeswoman said.

The UNE website describes Dr Pereg as a microbial ecologist with 25 years experience as a researcher in plant and social microbiology.

She obtained a PhD from the University of Sydney in 1998 and later worked for the Institute for Genetics at the University of Cologne in Germany before joining UNE in 2001.

The university has been contacted for comment.