The workshop alarm at farmer Scott Guy's property had been deactivated before 5am for the two weeks before his murder, a security firm worker told the High Court At Wellington.

Ewen Macdonald, 32, is charged with murdering his brother-in-law Mr Guy, who was shot in the driveway of his Feilding property on July 8, 2010.

The Crown says Macdonald shot Mr Guy at 4.43am.

Armourguard customer services representative Rebecca Kramer told the jury there were two monitored alarms on the farm which her company received signals from.

One of the alarms was called "shed", which referred to the workshop.

On July 8, the day of Mr Guy's murder, the alarm was deactivated at 5.02.51am, she said.

The Crown had told the jury that Macdonald was the one who deactivated the alarm on July 8 before milking began.

Earlier, a neighbour of the slain Manawatu dairy farmer described hearing three loud bangs on the morning he was found dead.

On the third day of Macdonald's trial in the High Court at Wellington on Thursday, Bonnie Fredricksson, who lived near the Guy property, told the court she was lying awake at about 5am, when she heard three loud bangs in quick succession.

It was from a heavier type weapon and the sounds were unusual for that time of day, she said.

Earlier, Mr Guy's father Bryan continued his testimony and was questioned further about a shotgun that was kept at the family farm in a cupboard. He had earlier admitted lying to police that he kept it in a safe.

He also recalled the phone call he took from Macdonald, telling him that Mr Guy was dead, but was not told he had been shot.

Mr Guy's sister Nikki Guy also recalled going to the scene, and trying to find out what happened.

She remembers Macdonald twice correcting David Berry, the man who found her brother's body, saying Mr Guy had been shot when Mr Berry thought his throat had been cut.

"I thought, David, being the first on the scene, would have got a closer look."