'Execution' of Tony McGrath arranged by woman he loved, Brisbane court told.

Brisbane rugby league referee Tony McGrath was killed in a “cold-blooded execution”, a Supreme Court jury has heard.

Tyson John Taylor has pleaded not guilty to murdering the 57-year-old, whose body was found two days after he was shot dead in the garage at his Woolloongabba home.

“He was shot in the head in his garage on the night of Tuesday, May 21st, 2013 by the accused man, Tyson Taylor, a man that had met him but once,” crown prosecutor Vicki Loury said in her opening address.

“What Tyson Taylor did that night was nothing short of a cold-blooded execution.”

The court heard a prostitute named Susan Stewart procured Taylor to kill Mr McGrath.

“She was a prostitute that McGrath believed he was engaged to, to be married,” Ms Loury said.

“She was a woman Tyson Taylor was also in love with. She was a woman who cynically manipulated both men, ultimately out of pure greed.

The court heard Mr McGrath had been financially supporting Stewart for a period of time.

“Mr McGrath had given Susan Stewart in excess of $500,000,” Ms Loury said.

She said the crown would argue Taylor also provided a substantial amount of money to Stewart.

‘Susan Stewart had a strong incentive to kill’

“Tyson Taylor had been a client of Susan Stewart and he had also given her significant sums of money,” Ms Loury said.

“Invoices suggest he had spent $20,000 on sexual services between August 2008 and February 2009.

“Susan Stewart had a strong financial incentive to kill Tony McGrath and she procured Tyson Taylor to do it for her.”

Extensive searches by detectives investigating Mr McGrath’s death failed to uncover a weapon.

Ms Loury alleged this was because Taylor ground down the sawn-off 22-calibre rifle.

The court heard Taylor had also been involved in an earlier, unsuccessful attempt on Mr McGrath’s life.

Mr McGrath was allegedly drugged before his house was set on fire in October 2012.

The jury was told he suffered significant injuries and had several toes amputated.

Taylor also pleaded not guilty to a charge of attempted murder.

The jury was told a covert operation involving 20 undercover police ultimately led to a taped confession from Taylor.

Ms Loury said it would be up to the jury to determine whether that confession was genuine.

The trial before Justice Martin Burns is set down to run for about three weeks and up to 100 witnesses could be called to give evidence.

This post originally appeared on ABC News.

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