Rye Hunt left his mate in the Rio de Janeiro airport and arranged to meet up again 30 minutes later.
Six days on, with his bank, email and social media accounts all untouched, Mr Hunt's family is desperate to find out what happened to him in that half hour.
"The international airport there - is, I believe - full of cameras, both inside and out," Mr Hunt's sister Romany Brodribb told AAP on Friday.
"And we have been really, really keen to see that footage."
Police have the exact details of where Mr Hunt and his friend were last together in the airport, and a description of what the 25-year-old was wearing.
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Ms Brodribb, from Hobart, said the family was trying to stay positive and focus on the search.
"We're obviously terrified and worried about his safety and well being," she said.
"We're curious, we want to know more details, we're frustrated that we can't get details as fast as we want them."
Brazilian police are seeking out CCTV footage, while DFAT and the Australian embassy are working with them to find Mr Hunt.
A spokeswoman for the Department of Foreign Affairs and Trade confirmed they were also providing consular assistance to his family.
Mr Hunt grew up in Tasmania and had been working in Kalgoorlie until he left the country on April 1.
He is an experienced traveller having also visited Southeast Asia and New Zealand.
A social media campaign to #findrye has been shared across Australia and South America.
"It's been heart-swelling," Ms Brodribb said.
"I've been contacted by expat Australians living in Rio just asking what they can do ... I've been contacted by locals in Rio and Brazil, offering to translate documents for us."
A crowd-funding page had raised more than $12,000 by 4pm Friday AEST to get one of Mr Hunt's family over to Rio to help push the search.
"We're just a little bit overwhelmed at how amazing the response has been," Ms Brodribb said.
