Scott Guy cousin killed in pub attack

Mr Marshall was a cousin of Mr Guy and was an usher at his funeral last July. Photo / Supplied

A 29-year-old New Zealander related to murdered Feilding farmer Scott Guy has been killed in a brutal attack in Western Australia.

Police say Andrew Marshall was having a drink with friends at a bar in Cottesloe, Perth, when he was pushed through a plate-glass window by a man a witness described as drug-crazed.

He fell 7m onto the footpath and died in hospital from head and spinal injuries.

The Herald understands Mr Marshall was a cousin of Mr Guy and was an usher at his funeral last July.

Mr Guy's sister-in-law Chanelle Bullock said last night she did not want to talk about Mr Marshall's death. It was "a hard time" for the family.

New Zealander Chloe Boyce-Bacon, 21, was in the bar when Mr Marshall was pushed out the window.

"We were all having a good time and then all of a sudden everyone ran over to the window. There was broken glass everywhere and you could see him lying there on the ground."

Ms Boyce-Bacon ran down the stairs to where people performed CPR on Mr Marshall for more than 20 minutes.

"It was horrible, absolutely horrible ... Everyone was a wreck. People were screaming and crying everywhere."

The man who pushed Mr Marshall out the window had earlier been trying to start fights with other people at the bar, Ms Boyce-Bacon said.

"He was obviously on drugs or something, he was crazy ... When they arrested him, before they put him in the cop car, he was yelling, 'I hope you die, I hope you die'."

Police say the 25-year-old has links to the Rock Machine bikie gang.

Acting Superintendent David Bryson said it would be alleged the attack was unprovoked. "This is a case of a young man on a Sunday night out with his friends having a beer and simply being at the wrong place at the wrong time," he said.

"This young man did not provoke anyone, that's what we will allege. He was simply grabbed and he was thrown through a level-two plate-glass window."

Mr Bryson said the arrested man was with gang members at the hotel.

Police said they had CCTV footage of the incident inside the hotel.

Mr Guy, 31, was shot in the throat in the driveway of his Feilding home in July last year.

He was married to Kylee and had two young sons - Hunter, 2, and Drover, who was born after the killing.

In April, his brother-in-law, Ewen MacDonald, was charged with the murder and is in custody.