As Australian backpacker Rye Hunt prepared to set off on an adventure around the world last month, he posted a smiling photograph of himself online alongside an excited message to his family and friends. 
"Embarking on an adventure now to see the world over the next few months. Unsure of what the future has in store for us," he wrote.
"Stay safe everybody, hope to see you all upon our return."
The 25-year-old, who grew up in Tasmania but had been working in Kalgoorlie before he left Australia, was sharing the journey with good friend Mitchell Sheppard.
He vanished after getting into a taxi outside Galeao International Airport in Rio de Janeiro in Brazil on   May 21. Now his worried loved ones are desperate to learn whether he is safe.
The last known photograph of Mr Hunt shows him carrying his large blue and black backpack through the airport just before 2.30pm on the day he disappeared.
The grainy image, taken from CCTV at the airport, shows him wearing a green Boston Celtics basketball singlet, denim shorts, and a black cap.
Mr Hunt had just had an argument with Mr Sheppard and had walked off alone, his family said.
It's understood the friends had organised to meet in 30 minutes, after taking time to cool off. They then planned to buy tickets to their next destination, Bolivia.
But Brazilian police say Mr Hunt got into a taxi a short time after the CCTV footage was taken, and there has been no trace of him since then.
In a troubling sign, police revealed overnight that they had recovered Mr Hunt's backpack, as well as his camera and laptop, Mr Hunt's family said in a statement on Monday.
The family said they were yet to learn where the backpack was recovered, or whether his wallet, iPhone and passport were inside the bag.
Mr Hunt has not used his phone or accessed his bank or social media accounts since the day he disappeared.
"The family are increasingly concerned about the welfare and safety of our Rye," his family said in a statement.
"We love him; we miss him; we just want him home.
"Rye is known among his friends and family as incredible generous and loyal and we know he would be very touched by the love and support shown to his family at this very difficult time."
Mr Hunts girlfriend, Bonnie Cuthbert, and his uncle, as well as Mr Sheppard's brother, are preparing to fly to Brazil this week to join the search.
Before his disappearance, Mr Hunt had been in contact with Ms Cuthbert daily.
"Holding onto all faith that I'm going to be reunited with my bear soon, stay strong and I LOVE YOU," Ms Cuthbert wrote online.
"My need to have Rye back safe in my arms cannot be expressed by words."
In the first leg of their six-month trip, Mr Hunt and Mr Sheppard had travelled to Thailand before flying to South America. They had then planned to travel on to Europe.
His family urged anyone with information to email Findrye@gmail.com