A hidden recording device worn by an undercover police officer captured the moment a woman accused of murder described how to start a house fire without getting caught.

The recording was played to the jury in the trial of Lynne Martin, 63, who is accused of murdering her father Ronald Russell Allison, 88, by setting fire to his house near Te Karaka, about 30km from Gisborne, in the early hours of January 25, 2013.

On Friday the jury heard evidence from the undercover officer, a young woman who used the name ‘Millie Tait’. Her real identity is protected under the Evidence Act 2006.

Millie was deployed by police to ascertain Martin’s involvement in her father’s death. She first met Martin and her husband Graeme in 2019 at the couple’s property near Matamata, where they provided spaces for tourists in campervans.

Over the next 18 months Millie built a relationship with Martin, in which the pair confided in one another. She would stay with the Martins on and off, for days or weeks at a time. She would dine with them, help around the house and frequently worked for the couple’s steam-cleaning business. When not there, she would call or text Lynne.

Millie’s cover story was that she had left Dunedin after a relationship breakdown with her ex-partner Chris, with whom she co-owned a property.

In Early 2020, she told Martin that she had lived in Australia five years earlier and had been at a party where a man sexually abused her. She said that when she drove home from the party she saw the man on the road and ran him down, causing serious injuries.

Millie told Martin that police in Australia had started looking into the hit-and-run and that Chris had a diary of hers in which she had written about hitting the man in her car. She told Martin that Chris was blackmailing her into signing over her half of the house to him, and said that if she didn’t he would give the diary to police.

In a conversation on the evening of July 20, 2020, Martin briefly proposed getting a friend of hers to break into the house to steal the diary and other items. Then she proposed another idea.

“Torch the house, there’s nothing left of the house, there’s insurance for you, the diary’s gone, and he is safe out of the house. Torch it,” she told Millie.

When Millie asked how she’d do that, Martin replied “there’s lots of ways... Arson is the easiest thing in the world and very hard to prove”.

Martin said it was the “easiest way for getting money, and the diary has definitely gone”.

She told Millie not to use an accelerant.

“You’ve got to keep right away from that because you will get caught, and it will be seen as arson,” Martin said.

She told Millie not to take her cellphone when she went to start the fire, not to leave fingerprints or DNA, and to prepare an alibi.

On the evening of July 23, 2020, Martin told Millie that the best way to start the fire would be by placing a pot of oil on the stove and turning the stove on high. She told Millie to take a litre bottle of oil into the house.

She then told her that actually cooking fats would be best, and showed Millie a container of Chefade lard.

“Even if you wanted to cook a big pot, two of those might even be better,” Martin said.

The trial, in the High Court at Gisborne before Justice Helen Cull, began on November 6 and was expected to run for up to five weeks.

-Marty Sharpe/Stuff.