Peter Falconio, 28, of Hepworth, disappeared on July 14 at remote Barrow Creek and is feared dead.
His girlfriend Joanne Lees, 27, managed to escape from the mystery gunman.
She is at home with her family in Almondbury for Christmas and New Year.
The couple had intended to end their travelling adventure in November.
The criminal investigation has been the largest in the history of the Northern Territory.
Now it has been scaled down to 14 officers in Alice Springs. But police said they still had plenty of clues and leads to follow up.
Tips from the public generated more than 5,600 lines of investigation.
Police have eliminated more than 200 potential suspects and 350 utility trucks similar to the one driven by the gunman.
Northern Territories Assistant Police Commissioner John Daulby said people were still ringing in with ideas.
There is a $250,000 reward for information leading to the capture of Australia's most-wanted man.
Mr Falconio's family and Miss Lees have maintained their hope that the mystery will be solved.
Mr Daulby said: "They are still optimistic and obviously we're very optimistic that we'll find Peter and that we'll find the offender. We've got to be.
"It's certainly the biggest criminal investigation that has been conducted in the Northern Territory and it will continue to be given that high priority."
The man tricked the couple into stopping their camper van on a dark and remote stretch of the Stuart Highway, 300km north of Alice Springs near Barrow Creek.
He tied and gagged Miss Lees and bundled her into the back of his truck and it is believed he shot Mr Falconio.
Miss Lees managed to escape into the sparse scrub and keep out of sight as the man searched for her with a torch and a dog for about an hour before driving away.
Three weeks after the crime, police released security camera pictures from an Alice Springs service station that showed a utility truck and a man with a moustache fitting Joanne's description of the gunman.
Mr Falconio's father Luciano and 31-year-old brother Paul arrived in Alice Springs within days of the tragedy.
Weeks later they returned home to comfort and support the rest of the family.
Miss Lees stayed on in Sydney, working in a book shop before coming home for Christmas.
Mr Daulby said: "I hope she never gives up on the investigation. We certainly won't give up on it.
"She will have an active role to play in the future of the case. It's important that we do maintain contact."
Her escape after a harrowing six hours hiding in scrub provided police with what could become their most significant clue.
Police found a sample of what they suspect is the gunman's DNA on her shirt.
If he commits another serious crime anywhere in Australia, his DNA could link him to the Barrow Creek case.