A "heartbroken" Mandurah woman who lost both parents in a car crash has been forced to replace a roadside memorial three times after it was targeted by vandals.
Falcon resident Lorraine Martin's parents died on April, 28 2005, heading home from an RSL meeting around the corner from their home.
A truck driver hit Peg and Eric Bury's car on the corner of Old Coast Road and Merlin Street.
Ms Martin said the driver was not using headlights.
"They always say accidents happen close to home," she said.
"They hadn't been drinking, just out to a meeting."
Ms Martin said her family erected a small cross the week of her parents' passing, which has been there for the last 13 years.
"We put new flowers around the cross and it's always been left alone," she said.
Someone has come and dug a hole around it and pulled it out after six days.
- Lorraine Martin
But, in the last three weeks, Ms Martin said her family had found the cross twice in nearby bush before it eventually disappeared.
"It's heartbreaking, why would somebody do this?" she said.
"We had a new cross and plaque made and concreted it.
"But someone has come and dug a hole around it and pulled it out after six days.
"I don't know how they did it, with the concrete at the bottom.
"Is it some sort of sick game?"
Ms Martin said she did not want to get another cross for this to happen again and wanted answers.
"As I pass it, I think of Mum and Dad," she said.
"Not only was it for our family, but also a reminder for drivers to be careful on the roads as people lost their lives there."
Mandurah Police Senior Sergeant Darren Hart said complaints like this are "extremely rare".
"Occasionally memorials are moved by Main Roads or local government for safety reasons but they do that in consultation with the family members, assuming they are able to work out who the family are," he said.
Main Roads spokesman Dean Roberts said they were aware the cross had been removed but "can confirm that this has not been undertaken by ourselves or our contractors".
City of Mandurah chief executive Mark Newman said the city was not aware of the circumstances surrounding damage to the roadside memorial.
“We understand the importance of these memorials to families and anything relating to them is done in consultation with the family,” he said.