Crown prepares case against Queensland mum accused of murdering adult children

Prosecutors have requested additional time to build the brief of evidence against a Queensland mother accused of murdering her adult children five years apart.

Maree Crabtree was in January charged with the murder of her 26-year-old son Jonathan last year and 18-year-old daughter Erin in 2012, following a complex police investigation across several states.

She was also charged with the grievous bodily harm and torture of a 25-year-old woman and several offences relating to frauds of large amounts of money.

Following her first court appearance, her lawyer said she would vigorously defend the charges.

Lead investigator Detective Inspector Mark Thompson has alleged the murders were "premeditated" and financially motivated.

"These acts haven't been compassionate acts of a stressed mother at her end," he said after her arrest.

"It was calculated, it was planned and it was executed with an end goal in mind."

During a brief mention on Monday, Brisbane Magistrates Court heard investigators hoped to have evidence ready by April 13 and the 51-year-old was listed to return there on April 23.