A mystery surrounds how or why an 18-year-old Australian was missing for almost nine weeks in bushland within a few kilometres of his Sydney home.
"We're waiting until he's well enough before we interview him," Detective Senior Constable Ben Wrigley said Monday.
Matthew Allen was reunited with his parents Sunday after two bushwalkers came upon him near a well-used walking track less than 2 kilometres from his home in Westleigh, which is 25 kilometres north-west of the centre of Sydney.
The accountancy student, who went missing November 27, is being treated in Hornsby Hospital after being winched out of bushland by a rescue helicopter.
Those who found him told police he was disoriented, partially blind and covered in leech bites that had become so infected that gangrene had set in.
Wrigley described the formerly 85-kilogramme Allen as "well" and said there were no fears he would not survive.
He said police had not expected to find Allen alive after 51 days on the missing persons list, but by the time they did, he had lost almost half his body weight.
Allen told rescuers he had survived only on water from a stream that had nearly dried up in a heatwave that gave Sydney its hottest ever day this month.
Allen left home without his mobile phone or any other belongings. Police became concerned for his safety after days went by and his bank account balance remained unchanged and no contact was made with family or friends.
There were reports that Allen had a medical condition, but this could not be confirmed.
There was speculation that he had hidden from search parties sent out to look for him, but this could not be confirmed because police have yet to speak to him.
Wrigley would not speculate on whether it was because Allen had become so disoriented that he could not find a walking trail and had then waited to be rescued.