The couple were on a backpacking holiday

Bradley Murdoch, 45, denies shooting Peter Falconio, 28, and abducting and assaulting his girlfriend, Joanne Lees.

His business associate James Hepi said he had discussed ways of getting rid of a body, including putting it inside a drain on the side of the road.

The six-week committal hearing will decide if Mr Murdoch will face a trial.

Mr Hepi told Darwin Magistrates Court that, around the time of Mr Falconio's disappearance, he had seen Mr Murdoch making handcuffs out of wire cables "very similar" to a replica of those Ms Lees had said were used to tie her hands behind her back.

Mr Murdoch had been on one of his regular trips across the central Australian outback at the time of Mr Falconio's disappearance on a lonely stretch of the Stuart Highway north of Alice Springs three years ago, Mr Hepi added.

The appearance of the vehicle changed dramatically James Hepi

"The appearance of the vehicle changed dramatically," he said.

"It was heavily modified," Mr Hepi added.

He also told the court Mr Murdoch had had two hand guns - a big, heavy revolver and a smaller one, which he wore in a holster beneath his clothes or kept in his car.

Ms Lees has said a truck driver pointed a silver Western-style, long-barrel revolver at them after flagging down Mr Falconio's van and saying sparks were coming from its exhaust.