A Queensland teenager who murdered her grandfather in Adelaide helped him apply a bandaid to one of his stab wounds, then washed the dishes as he lay dying in the kitchen, court documents have revealed.

Key points: Pair drove to Adelaide from Queensland to kill Mr Whitwell and steal his life savings

Pair drove to Adelaide from Queensland to kill Mr Whitwell and steal his life savings Dwyer stabbed him in the neck and chest while Burns waited outside

Dwyer stabbed him in the neck and chest while Burns waited outside Women searched the house for $114,000 in cash but could only find $1,000

Brittney Jade Dwyer was 19 years old when she murdered her 81-year-old grandfather, Robert Whitwell, at his Craigmore home in Adelaide's north in August last year.

She pleaded guilty to murder and her girlfriend Bernadette Burns pleaded guilty to an amended murder charge, reflecting she intended to rob Mr Whitwell and commit violence.

Documents released by the Supreme Court have revealed the pair's murderous plot.

They show the young women drove to Adelaide from Queensland with the intention of killing Mr Whitwell and stealing his life savings, nearly $114,000 which he kept hidden in cash at his home.

The documents reveal Burns originally said she wanted to watch Dwyer kill her grandfather, but then decided to wait outside in the car and put her make-up on while it happened.

Robert Whitwell kept his life savings in cash hidden at his property. ( Supplied: SA Police )

After going into the house and looking at childhood photographs and videos with her grandfather, Dwyer sent Burns a text message saying she didn't think she could go through with it, the documents revealed.

Ms Burns told Dwyer "she could not back out now because they had come all this way" and told her to "just harden up and do it", the documents reveal.

As Mr Whitwell began to walk Dwyer out she pulled out a knife and stabbed him in the neck, then in the chest and again in the neck, the documents stated.

They reveal that after being attacked Mr Whitwell managed to get himself into the kitchen, where Dwyer helped him put a bandaid on one of the stab wounds on his neck and handed him a cloth.

The documents reveal Dwyer washed the dishes while her grandfather died and then sent a text message to Burns saying "it's done".

The young women then searched the house but could not find Mr Whitwell's life savings and instead stole $1,000 from his wallet and other valuables, the documents stated.

Family statements point to troubled history

Statements tendered to the court from Mr Whitwell's family members said he was a generous and "old-fashioned man" who loved his family.

The statements reveal Dwyer had mental health issues as a teenager, had a history of self-harming, a "moody personality" and wrote some "very dark and moody" posts on social media.

They also revealed she used to chase her older brother around the house with a knife when she was about eight years old.

Dwyer and Burns remain in custody and will return to court for sentencing submissions next month.

Dwyer's ex-girlfriend, Shelby Lee Angie Holmes, 19, received a suspended sentence for trespassing in Mr Whitwell's home with Dwyer a couple of months before the killing when they had originally planned to rob him.