Prison guard Dean Yarnton​ and his wife Sharon both called triple-zero asking for help in the middle of the night.

Mr Yarnton reported waking up in his ute at Picnic Point, with "fuel all around" and two empty gas bottles in the back. When police arrived at Henry Lawson Drive, before 2am on February 1, 2015, Ms Yarnton said her husband had attacked her.

Ms Yarnton, 50, a former high-ranking prison guard who had been married to Mr Yarnton for 23 years, is now on trial accused of trying to blow him up.

The NSW District Court has been told there was animosity between the Yarntons, after Ms Yarnton found out her husband was having an affair with one of their colleagues.

Constable Catherine McGuinn said Ms Yarnton told her she took a wrong turn on the way home from dinner at the Merrylands bowling club and ended up in the national park.

According to Constable McGuinn's statement, aired in court on Tuesday, Ms Yarnton said: "I really needed to chuck a s---, so I went into the bushes.

"I just came out of the bushes and Dean was going on. He told me he was going to kill me, I didn't know what was going to happen, but Dean's a big drinker.

"I just wanted to get away from him so I ran and then he started to throw gas cylinders at me ... I threw a couple back, so my fingerprints will be all over them."

Constable McGuinn said after she took Ms Yarnton to Bankstown police station and removed her clothes and handbag, she noticed a strong smell of petrol coming from the bag.

Ms Yarnton has pleaded not guilty to attempted murder, as have her accused accomplices Monique Hayes, 25, and Fady Houda, 24.

Ms Yarnton is accused of coming up with an elaborate murder plot, including allegedly making up stories about loan sharks coming after Mr Yarnton in early 2015, and allegedly spiking his drink during dinner with friends at the bowling club. 

Martin Hoang​, a member of the State Emergency Service, told court he drove past Mr and Ms Yarnton that night and stopped to ask if they needed help.

"I asked him what happened and he said he woke up in the car and there was petrol all over the car," Mr Hoang told court.

"That's when I walked to the back of the ute and I saw a little pond of petrol in the tray."

Mr Hoang said he asked Mr Yarnton if it was his fuel.

"He said 'No, my car runs on diesel'."

The trial continues before Judge Paul Lakatos​.