The teenage girl who survived axe attack that killed her family is unlikely to ever remember what happened.

A teenage girl who suffered horrific injuries in a brutal axe attack that killed her mother, father and eldest brother, is unlikely to ever know for sure what happened.

A year ago today, millionaire businessman Martin van Breda, his wife Teresa and their eldest son Rudi, 22, were killed in a frenzied axe attack.

The family was at home in their South African mansion in the exclusive gated De Zalze Winelands Golf Estate in Stellenbosch, east of Cape Town.

Marli, then 16, and her brother Henri, 20, both survived the attack.

Marli, a former Perth student, was found with serious head wounds and a severed jugular. She suffered brain injuries, and her lawyer said this week that she is unlikely to fully regain her memory.

“Marli is doing very well. Her recovery has been nothing short of miraculous given the extent and severity of the injuries that she sustained,” Louise Buikman said.

“She is very well physically. Mentally, she is also coping remarkably well.”

Marli lives with her aunt and uncle, and is said to be recovering well.

“She is obviously terribly sad about the loss of her parents and her brother. [But] Marli and her family wish to grieve in private.”

Marli has retrograde amnesia. She spent six months in intensive rehabilitation last year.

She is back to school this year, but Buikman said she would not be able to help unravel the mystery surrounding the attack, given her lack of memory.

Investigators are yet to make any arrests over the murders, and there is ongoing speculation that Marli’s brother Henri might have been involved.

Reports claimed that Henri took four hours to call paramedics after the attack, and that his injuries, all minor, could have been self-inflicted.

Henri has blamed the attack on an intruder, but no trace of the assailant has been found.

In the emergency call, Henri can be heard calmly saying: “My family and me were attacked by… a guy with an axe”.

He says his family members were “bleeding from the head” before giggles can be heard.

Marli and Henri do not live together, but are in regular contact.

While the investigation into the attack is ongoing, there is a chance that no one will be charged.

A coronial inquiry is still to be held into the murders.