Matthew Allen, 18, disappeared from Westleigh in northwest Sydney, Australia, in late November. For the next nine weeks, his cell phone and bank accounts went untouched. Extensive searches turned up nothing.
Last Saturday, two hikers found him.
Remarkably, he was alive.
Allen was discovered lying in bushland less then two kilometres from his home. He was covered in leeches and insect bites and lost almost half his body weight.
"He'd lost about 30-40kg," one of his rescuers told The Daily Telegraph.
The teen, who suffers from an undisclosed mental illness, was exhausted, disoriented, severely dehydrated and was suffering from both partial blindness and gangrene to his lower legs and feet.
AFP reported that police were shocked the teen survived.
"He was not living under any shelter and was exposed to the full conditions since reported being missing," said acting police inspector Glyn Baker.
Allen told his rescuers that he survived by drinking from a local creek that has since almost completely dried up. Record-breaking heat — temperatures soared to 46 degrees Celsius in recent weeks — put his life at risk.
"I was amazed and very happy that everything turned out they way that it happened,'' Detective Senior Constable Ben Wrigley from Hornsby Local Area Command told the Daily Telegraph. "I couldn't believe it.''
"Anyone who is missing for that length of time in those kind of conditions - you wouldn't expect to see them again," he told AAP.
The teen was airlifted to nearby Hornsby Hospital where he is undergoing treatment for his injuries, none of which are life-threatening.
"His family are ecstatic that he's alive and that he's well," Baker told the AFP.
Police believe he spent the entire nine weeks in the wild.