A teenager who murdered Adelaide pensioner Anne Redman has been described by the victim's family as a gutless coward.

Ms Redman's throat was cut seven times with a blunt hunting knife on Australia Day last year.

She had gone outside her house at Seacliff with a torch at night and in her pyjamas after she heard the sound of breaking glass.

The court was previously told two teenagers allegedly had cut the power, smashed a window and were planning to break into the home on Yacca Road.

One of them, who is a policeman's son, pleaded guilty to murder and the other will stand trial later.

In their victim impact statements, Ms Redman's relatives described her as a cherished and loving mother and sister, who was intelligent, witty and fun.

The husband of Ms Redman's youngest daughter - who found the 87-year-old woman's body - told the teenager in court he was a sad, pathetic and gutless coward for having bragged about his despicable crime.

Ms Redman's family said he deserved a punishment no court could give.

Youngest daughter Suzanne Redman spoke of the terror of her mother's final moments of life.

"My mum's final moments were nothing short of indescribable terror. Her home of 50 years had been violated," she said.

"My mum was 87 years old, partly deaf, she was dressed in a summer cotton nightie, bare-footed and alone.

"It's incomprehensible for everyone. For me it's pure evil. I can only assume mum's murder was a satanic thrill kill."

Grisly souvenirs

Ms Redman said she was further distressed to know the teenager kept trophies including the knife and the torch her mother had used.

Her husband Chris Miller told the court he was still haunted by the trauma of finding the body in the backyard.

"I was planning to watch the cricket when Suzanne rang me to say she was at her mother's house and something was wrong," he told the court.

"The following sequence of events, I can clearly recall every aspect in great detail, even though I would prefer to forget aspects of that day.

"She was lying on her side wearing her nightdress with a very large pool of blood near her head. The sight of Anne lying like this is one I will never forget, it is burnt into my head and distresses me greatly."

At times he looked directly at the teenager in the dock, as the boy sat with his head bowed.

"You are a sick, pathetic, gutless coward. Your murder of a defenceless 87-year-old woman in the house where she felt safe and secure for more than 50 years, while hiding behind a balaclava, is worth punishment this court can't give," he said.

"You then bragged about your actions. I don't know what is wrong with you but I know it can't be fixed.

"You are a disgrace and you make me sick."

Another daughter Karen Batsiokis said her mother had been a gentle and loving person.

"I visited my mother once a week for the last 30 years, she was a wonderful mum, a friend, a wise mum, she had a lot of life left to live. She may have been 87 years old but she was fiercely independent," she said.

"Preying on the elderly couldn't be more cowardly and gutless. I do not see remorse.

"You must be a callous, hateful person. You didn't even stop when my mother screamed. I am filled with rage and anger. You bragged about the shocking violent death she suffered."

A victim impact statement from Ms Redman's two surviving sisters, aged 87 and 91 was read to the court on their behalf.

They said that since their sister's murder they had become too scared to do the social activities they used to do together.

"We have lost our trust in people except those close to us," their statement said.

"We have always been fiercely independent for our whole lives. This has been taken from us."

Sentencing submissions will continue later in the month.