Murderer had co-accused women under spell

Aaron Bunch
Two more people linked to the murder of a Queensland father have been sentenced

Two vulnerable women under the spell of a violent and manipulative killer helped him plot the bloody murder of one of their ex-husbands, a Queensland court has heard.

Marilyn Ann Ryan, 39, and Jessica Lee Roebuck, 22, claim they had no idea Mark Stephen Crump, 38, would brutally mutilate Gary Ryan, 43, with a sword and leave him dying in a pool of his own blood.

The pair, who were 19 and 21 when they "fell into the clutches" of convicted murderer Crump, believed his journey to Mundubbera in August 2016 was simply to threaten Mr Ryan following a custody dispute.

It wasn't and Ryan and Roebuck were sentenced on Friday to eight and six years respectively for manslaughter after police discovered they helped Crump prepare for his journey to Mr Ryan's home near Bundaberg.

They also lied to the police and set up a false alibi for their shared lover at their home in Orange, in regional NSW, after Crump and his friend Trevor Spencer, 73, lured Mr Ryan from his home and stabbed him in the head and neck 59 times.

The men's "horrid" attack was so frenzied they stabbed each other and an undertaker refused to show Mr Ryan's family his body because it was too mutilated, the Brisbane Supreme Court heard.

In sentencing, Justice Martin Burns acknowledged the power Crump wielded over the two women, saying Ryan was not equipped to deal with him and Roebuck had been preyed upon.

"He was by all accounts the dominant figure and you were very much dependent," he said while addressing Roebuck.

"He exploited you in many ways and you felt yourself powerless to stop him ... you were emotionally dependant on him ... you did everything he asked of you."

Justice Burn said Crump was manipulative and controlling of the two vulnerable women and that Ryan had "learned at his hands" through varied forms of abuse she must do what she was told.

The court heard she endured 12 years of psychological and physical abuse and had become "pathologically co-dependent" on Crump as a result.

More than 100 pages of letters between the pair after they were taken into custody revealed the level of mistreatment and that Crump had threatened Ryan before she provided him with an alibi, he said.

Despite this, Justice Burns said both women had played a part in a serious offence "that led to the death of a good and decent man in a most brutal fashion".

He made note that their part was to assist Crump with his plan to threaten Mr Ryan and not to kill him.

With time served both women were eligible for parole immediately.

Crump and Spencer were convicted of murder and sentenced to life in prison on Thursday.