O'Dempsey's one-time girlfriend Kerri-Anne Scully on Wednesday told the hearing her former beau - who also had a short-lived relationship with her mother years before - confessed to the killings as they perused a book he was mentioned in.

"He said he was good for the McCulkin murders but they'd never get him for it," she told the Brisbane Magistrates Court.

The court heard O'Dempsey then suggested his total was actually 33 - to which Ms Scully replied, "that's a lot".

She ended the relationship soon after but said O'Dempsey instructed her to tell a subsequent partner to leave Queensland or else he'd "take care" of him.

Ms Scully's evidence came after a former neighbour of Barbara and her girls described once seeing O'Dempsey and another man, later presumed to be Dubois, at her Highgate Hill home in the early hours of the morning.