WA policeman testifies in gunfire trial

"It was just a fight for my life. I thought I was going to die."

That was how Sergeant Michael Richard Williams described his violent struggle with Russell Graham Penny, who is on trial in the WA Supreme Court over their November 2013 altercation.

Penny was shot in the stomach by Sgt Williams' partner - who is also the officer's fiancee - after the pair fought over a sawn-off shotgun, the court heard on Monday.

Sgt Williams testified that Penny was pulled over on Albany Highway in Crossman because the rear tail light of his vehicle was broken.

He said he planned to check the driver's licence, conduct a breath test and inspect the vehicle, but when he approached Penny, the accused man said: "What's your f***ing problem? I just want to piss."

Sgt Williams said he was anxious and concerned for his welfare as Penny walked off to urinate in some bushes.

"My senses were a little bit heightened," Sgt Williams said.

The officer shone his light at Penny to keep an eye on him in the otherwise dark area.

When his partner returned from the police car having checked Penny's licence, she told Sgt Williams it was a "420 Christmas tree" - a non-police term the pair used to indicate something suspicious.

Sgt Williams believed from Penny's demeanour that he might have been affected by drugs or alcohol.

Penny returned with his left hand concealed by his shirt and his right hand in his pocket, the court heard.

Sgt Williams said Penny repeatedly refused to show his hands when asked, so he grabbed his left hand to reveal what the accused man was hiding.

"That's when it kicked off," he said. "The struggle became violent."

Sgt Williams deployed his taser on Penny's back but it did not work, so the officer tried and failed again.

He stepped back and then heard his partner yell out "drop the gun" three times to Penny.

Sgt Williams said he tried to wrestle the weapon from Penny, who seemed to have "extraordinary strength".

"I was trying with all my strength to break his grip," he said.

While the struggle lasted only about 15 seconds, he said it felt like an eternity.

"I thought that if I didn't have the ability to break the grip of the accused, I was going to be shot," he said.

They fell to the ground and Sgt Williams said he started to feel exhausted but continued to slam the gun onto the ground to release Penny's hold.

With the barrel just 15cm from Sgt Williams' face, a shot was fired and he said he saw sparks.

"I'm losing the gun," he told his partner and repeatedly shouted for her to shoot Penny, which she did.

"I was in fear that I was going to be shot and killed," he said.

Sgt Williams said Penny finally "deflated" and he took control of the gun.

The trial continues.