Christina Rowlands, now 26, was 23 when she was critically injured by the ex-partner of a female friend who aimed a .44 calibre rifle at her and shot her during a murder-suicide in October 2011.

An emotional Ms Rowlands was one of four witnesses to give evidence before coroner Michael Brett in the Devonport Court at the inquest into the deaths of her partner Benjamin Aherne, 31, and John Clements, 46, who shot and killed Mr Aherne after he shot Ms Rowlands.

Clements then shot himself dead.

Ms Rowlands, a Woolworths employee, told the first day of the inquest that Mr Aherne had gone to 128 Watkinson Street to the home of her nurse friend, Kylie Hales, after Ms Hales rang him for help after she was assaulted by an upset Clements.

The inquest heard Clements went to the house of his ex-partner that Saturday morning expecting to participate in a threesome he was invited to, which did not happen. The inquest was told a threesome already happened at the house with another man.

Ms Rowlands said she drove her own car to Watkinson Street because she had a ``gut feeling'' to follow Mr Aherne to make sure everything was alright after he drove there in his work ute before her.

When Ms Rowlands arrived she saw Clements in the driveway standing near his car with a rifle in his hand.

She told the inquest Clements was surprised to see her and would not have known Mr Aherne was inside.

Ms Rowlands got out of her car and Clements told her in a cold voice to leave.

``He said: `Chrissie leave','' Ms Rowlands told the inquest.

``He wanted me out of there.

``He didn't yell it was firm, it was cold.''

Clements went to the back of the house out of her sight.

Ms Rowlands got back in her car, turned the ignition on and reached for her phone to call police as Mr Aherne came running out of the house.

``He banged on the (car) window and he was screaming at me to `get out of there','' Ms Rowlands told the inquest.

``John (Clements) appeared at the passenger side of the car and he raised his gun at me and he shot me.''

Ms Rowlands said Clements said rather loudly: ``I'm not going to jail.

``Then he shot again at me and struck me. I ducked between shots.''

Ms Rowlands described hearing a further two or three shots behind her and the sound of screeching tyres as if someone arrived.

Ms Rowlands said Ms Hales came to the car and was saying she was ``sorry baby'' and yelling for someone to call an ambulance.

Ms Rowlands said she did not know what motivated Clements.

``I don't know why he did it,'' she said.

She told the inquest Clements still had a relationship with his ex, Ms Hales, and what she wanted he gave her.

Ms Rowlands said there was no problem between Mr Aherne and Clements.

``Before it happened he (Clements) said to me he was glad that I had someone like Ben,'' she said.  

Ms Rowlands said she didn't know whether Clements was aware of what was happening at the house entirely before he'd arrived there after finishing night shift as an aged care worker at Meercroft about 7am.

Earlier that morning Ms Hales and another woman Clements was involved in a sexual relationship with, Helen Scott, had participated in sex with each other and with Ms Scott's ex-husband Tim Scott, who was a police officer at the time.

The inquest heard the two women were texting and talking on the phone to Mr Clements while he was at work during the night.

After having sex Mr Scott left the house before Clements was expected to arrive.

The inquest heard that when Clements got there expecting a threesome with the women it did not happen.

The inquest was told he assaulted Ms Hales after she kicked out at him from the bed she was naked in.

After Clements left upset, Ms Scott called her ex-husband about what happened with Clements and Mr Scott returned to the house.

Mr Scott gave evidence that he told Ms Hales to call the police.

Mr Aherne arrived and Mr Scott said he gave him the same advice to call police. 

Mr Scott and his ex-wife then left Watkinson Street before Clements came back to the house again  about 7.30am with a gun.

The inquest heard that Clements was involved in a scuffle with Mr Aherne as he was protecting Ms Hales.

After Mr Scott heard of the murder-suicide he came to the scene and was spoken to by police, but omitted to say he'd been there earlier.

Mr Scott has since lost his job as a police officer after being found guilty of making a false statutory declaration.

The inquest continues today.