The parents of Sydney man Matthew Leveson are "absolutely devastated" after their son's memorial site was vandalised on the eve of his funeral.
The late 20-year-old's father, Mark, says nothing was left on a tree in the Royal National Park, near where his remains were found.
"Absolutely devastated," Mr Leveson tweeted on Thursday night, alongside a photo of the bare tree.
"The night before Matty's funeral we visited his memorial tree in the National Park to find it vandalised. Butterflies taken, gifts taken, memorial plaques taken, fresh flowers taken."
Matt's mother, Faye, said her "heart was broken".
"How could someone do this on the eve of Matt's funeral," she posted on Twitter.
A spokeswoman for NSW Environment and Heritage on Friday said rangers did not remove the tributes and they did not know who was behind the vandalism.
After a decade-long search for his body, the couple will finally lay their son to rest on Friday in Sydney's south.
Matt was last seen leaving Darlinghurst's Arq nightclub in September 2007 with his then partner Michael Atkins who was later acquitted of murder.
Atkins led police to the location of Matt's remains in the Royal National Park after complex legal agreements were struck, and his remains were found in mid-2017.
Mark and Faye have asked guests at Friday's ceremony, which will take place at the Woronora chapels in Sutherland, to wear bright colours and a splash of Matt's favourite colour purple.
"It's meant to be a celebration of his life, being grateful for the 20 years that he was alive," Mark Leveson says. "It's a fun day."
The service will include Matt's favourite songs, photographs and stories to show guests what he was like through his childhood, schooling and early adulthood.
Deputy state coroner Elaine Truscott in December wasn't able to rule on the cause of Matt's death, despite a lengthy inquest, but said Atkins' lies were suspicious.
But on Friday there'll be no mention of the manner in which the 20-year-old's life was cut short, nor the subsequent court cases, inquests and searches.
"We just want to remember Matt," Ms Leveson says.
Detectives finally found Matt's body in May 2017 beneath a cabbage-tree palm that has since been relocated to Mark and Faye's backyard.
The Levesons had long promised Matt they would give him a proper farewell.
"All those years of searching, we finally achieved our goal and it's made it all so real," Mr Leveson says. "This will be our final goodbye to him."
Australian Associated Press