It has been four years since Nick Veljanovski, 28, was last seen.
There is still no trace of the young man who went missing in the Royal National Park on June 11, 2014.
Several witnesses saw him on a walking track that afternoon. Only his car was found.
This first week of August is National Missing Persons Week.
In Australia there are more than 2600 people listed as a long-term missing person (missing for more than three months).
Nick, of Bankstown, was last seen last in Yagoona on the morning of June 11.
His long-term relationship with his girlfriend is believed to have ended in the lead-up to his disappearance with the pair arguing over the phone on the day he disappeared.
She reported him missing that night when he did not come to her house.
A $50,000 reward is still on offer for credible information that leads to his whereabouts.
He is part of a missing person campaign Invisible Friends by Missing Persons Advocacy Network, a non-profit organisation that provides support and advice to families and friends of missing persons.
It promotes the use of social media to help find loved ones.
People can ‘add Nick as a friend’ and Facebook uses facial recognition technology with a 98 per cent accuracy rate to help find him.
The profile is invisible and sits in a user’s friendship list.
His family and friends also continue to post reminders on his Facebook page, nickcomehome, to help find him, but there have been few clues.
His mother Sylvia is not giving up.
“Four years on we are still holding on hope and still desperate for answers and some sort of closure,” she said.
“There were a couple a sightings at Port Stephens last August but it’s gone really quiet.
“We are desperate for any information, and I feel that someone knows something.
“If he needs time out we understand.
“Ideally we’d like him to walk through the front door but if Nick gets this message we just want to know he’s OK to put our minds at ease, especially because we haven’t found any remains or a body.
“But at the same time, if he has passed on we need to know that and try to move on.
“Not knowing is the hardest.”
Anyone with information should contact Crime Stoppers on 1800 333 000.