The lawyer for a Gold Coast mother accused of murdering two of her children and torturing a third says her client will be “vigorously defending” the charges.

Police have charged Maree Crabtree, 51, with two counts of murder, one count of torture and one of grievous bodily harm, claiming the deaths were “financially motivated”.

Her 18-year-old daughter Erin Crabtree was found dead at an address in Maudsland on September 4, 2012, and on July 18 last year the body of her 26-year-old son Jonathan Mark Crabtree was located at a home in Upper Coomera.

Ms Crabtree is also facing further charges of fraud, attempted fraud and robbery while armed.

Detectives from the Gold Coast Criminal Investigation Branch with assistance from the Homicide Investigation Unit have charged a woman in connection to the suspected suspicious deaths of an 18-year-old woman and 26-year-old man. https://t.co/BrRBMCssje pic.twitter.com/kZj5anGIas

— Queensland Police (@QldPolice) January 24, 2018

The ABC has reported police will allege both Jonathan and Erin Crabtree suffered impairments due to the long-term administering of prescription drugs.

Police also allege the woman seriously assaulted her 25-year-old daughter on multiple occasions over several years.

Complex investigation is ongoing

At a media conference on Wednesday afternoon, Detective Inspector Mark Thompson said the police investigation was extremely complex.

“The family in question have a significant history within New South Wales and other states of Australia,” Inspector Thompson said.

He said police would allege the killings “haven’t been compassionate acts of a stressed [mother] or a mother at her end, we will be alleging these were premeditated direct acts of murder that have been perpetrated on the victims”.

“The deaths themselves, we will be alleging, were financially motivated.

“The actual method of murder is something that will be very finely picked over in a court of law so I don’t want to expand on that at this time.

These are premeditated and calculated financially driven crimes.”

The woman was arrested at a house in the Brisbane suburb of Coorparoo on Wednesday morning and taken to the Brisbane watch house where she was interviewed.

Police allege between March 2011 and August 2013 Ms Crabtree dishonestly gained an insurance payment of $567,863.

She then allegedly attempted to dishonestly gain a benefit for herself through a Sunsuper superannuation death benefit policy of $125,000 between March 2017 and September 2017.

Police further allege she attempted to dishonestly gain a benefit for herself via a total permanent disability claim of $238,800 during that time period.

Jonathan Crabtree as pictured on Maree Crabtree’s Twitter account. Photo: Twitter/ABC

Police said more information from the public was being sought.

“We are appealing for anyone who may have any information that could assist with the investigation,” Inspector Thompson said.

“Any piece of information, no matter how small can have a significant impact on our investigation.”

He said anyone who had concerns about the abuse or exploitation of vulnerable people should call police.

– with ABC, AAP