Police have arrested and charged a Gold Coast mother after a lengthy investigation into the deaths of her two disabled children.

The 51-year-old woman was arrested in the Brisbane suburb of Coorparoo earlier today after new information was provided to detectives suggesting their deaths might be suspicious.

Police will allege the woman, believed to be from the Gold Coast suburb of Maudsland, was slowly poisoning her 18-year-old daughter and her 26-year-old son before they both died five years apart.

Both of her children were believed to have had severe disabilities.

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The woman's daughter died on September 4, 2012, and her body was found at a Plantation Crescent home in Maudsland.

Five years later, on July 18, 2017, the woman's son was found dead at a Fig Court, Upper Coomera address.

Both of their deaths were originally treated as suicide.

Police will also allege a 25-year-old woman was found in the Coorparoo address who had been seriously assaulted on numerous occasions over several years.

The woman was known to all three alleged victims.

The woman is expected to appear in Brisbane Magistrates Court later today.

She has been charged with two counts of murder, one count each of torture and grievous bodily harm.

The 51-year-old sat in the back of a car with detectives. Photo / Channel 9
The 51-year-old sat in the back of a car with detectives. Photo / Channel 9

The woman has also been charged with two counts each of fraud and attempted fraud, and one count of robbery while armed.

Detective Inspector Mark Thompson said the investigation has been complex as some of the alleged incidents occurred across Australia.

"That is why 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."