A brothel madam accused of arranging the murder of Brisbane Rugby League Referees Association president Tony McGrath has failed in her bid for bail.

A brothel madam accused of murdering a Brisbane rugby league identity will remain behind bars after a judge denied her bid for bail.

A Supreme Court judge ruled there was a risk Susan Ellen Stewart would flee or interfere with witnesses.

Stewart, 45, is charged with procuring another man to kill Brisbane Rugby League Referees Association president Tony McGrath.

Mr McGrath, 57, was shot dead in his Woolloongabba garage in May last year.

Stewart was arrested in February.

She applied for bail in Brisbane on Tuesday but the application was refused.

“I consider that there is a very real concern that given the strength of the Crown case she may not appear or in fact may interfere with witnesses,” Justice Ann Lyons said.

Prosecutors allege Stewart was in a relationship with Mr McGrath and had persuaded him to modify his will in her favour.

They say the former prostitute falsely told Mr McGrath she was pregnant with his child so he would make her the sole beneficiary of his will.

Mr McGrath modified his will but did not sign off on it, though Stewart believed it had been changed, the court heard.

She allegedly procured a man who worked as a driver at her Tweed Heads brothel to kill Mr McGrath in 2012 and again in 2013 after the first attempt failed.

During Tuesday’s bail application it was revealed Stewart had allegedly been in similar relationships with six others who, like Mr McGrath, were lending her money.

One of the men was Mr McGrath’s alleged killer, Tyson John Taylor.

The loans were in the tens of thousands of dollars and one lender gave Stewart, who was in debt, at least $200,000, Crown Prosecutor Dennis Kinsella said.

The six men are crown witnesses and are among 192 people who have provided statements to police.

Police claim to have secretly recorded Taylor admitting to the murder and talking about the earlier murder attempt, which allegedly occurred in October 2012.

They say in that case Stewart and Taylor drugged Mr McGrath and tried to set fire to his unit but succeeded only in burning his feet so badly he lost three toes.

In May 2013 Taylor allegedly finished the job, shooting Mr McGrath in the face with a .22 calibre rifle after the referee returned home from a meeting.

Both Stewart and Taylor are behind bars charged with murder, attempted murder, arson, grievous bodily harm, administering a stupefying drug and entering a dwelling with intent.

Taylor has also been charged with robbery with violence while armed and weapons offences.

Defence barrister Kate McMahon said the Crown’s case against Stewart was circumstantial with no direct evidence her client procured Taylor to kill Mr McGrath.

She suggested others might have had a motive for the murder and referred to infighting at the referee’s association.

However, the judge agreed with Mr Kinsella that Stewart, who is facing a life sentence if found guilty of murder, could be tempted to flee or interfere with witnesses.

Justice Lyons refused bail despite a $30,000 surety offered by Stewart’s brother, who was in court along with other family members to support her.