The Adelaide father of a teenage girl shot dead by her boyfriend’s father says his best friend has been stolen and his heart shattered with the last moments of her life haunting him the most.

Greg Ireland has told the Supreme Court he was living the “deepest, darkest nightmare” following her murder in August last year.

“Her last moments knowing she was about to be shot must have been horrendous,” he said.

Before the court on Monday was Pawel Klosowski, 46, of Mount McIntyre, in South Australia’s southeast, who previously pleaded guilty to the murders of his son Lukasz Klosowski and Chelsea Ireland, both aged 19.

Police had been called to his property after reports of a shooting and arrested Klosowski without incident.

In sentencing submissions, the court received 22 victim impact statements, many from relatives of the two victims.

Lukasz Klosowski and Chelsea Ireland were shot dead on a rural property in South Australia. Photo: ABC

The court also heard that it was Chelsea who called triple zero on the night of the killings after trying to take refuge in a bathroom.

Ms Ireland’s mother Deborah Ireland told the court that her daughter would have been so scared at that moment and the “imagery of her final minutes haunts me”.

“I feel so fragile, so broken, like I’m constantly teetering on the edge,” she said.

“I feel like I’m living in some horror story.”

Because of his early guilty pleas, Klosowski could receive up to a 40 per cent discount on his non-parole period.

Such large discounts are no longer possible under changed SA laws.

The sentencing hearing was continuing.

-AAP