Debbie Martyr's orang pendek sighting, Kerinci Seblat National Park, Sumatra (1994)

Debbie Martyr first came to Sumatra in 1989 as a travel writer. She climbed Mount Kerinci. There she heard about the orang pendek, a small upright primate of local folklore. By 1994 she was back in the forests of Kerinci Seblat National Park. She did not believe in the Abominable Snowman. She did not believe in Bigfoot. "At first I thought the same, that it was just a myth," she later said.

September 1994. The Gunung Tujuh area of the park. Martyr remembered it as the middle of the month, four months into her stay. Later summaries give 30 September.

A shallow valley lay in sunlight. Something was crossing it, about 30 metres away. It moved upright through hip-high vegetation. It stood about a metre tall, covered in short dark fur, with immense strength in its upper body. It seemed to be trying to avoid being seen.

She called it "small yet immensely strong, and definitely a non-human primate." Not like an orangutan. More like "a siamang or an agile gibbon on steroids." Its coat, she said, was "a gorgeous colour."

"I had a camera in my hand at the time but I dropped it I was so shocked," she told Richard Freeman in 2004. Other retellings say she froze, or chose not to photograph it. Either way, no picture was taken. As she put it to VIVAnews in 2013: "I did not meet it, but I saw it."

In March 1995 Martyr returned with numerous consistent eyewitness accounts and plaster casts of footprints. Freeman described her cast as about 8 inches long, with four forward-facing toes and the big toe set further back.

Fauna & Flora International backed a project with photographer Jeremy Holden that ran for about 15 years. Camera traps went into the forest, with LIPI and park staff taking part. They caught rare animals, including the Asian tapir. They never caught an orang pendek. Martyr said she saw the creature again in 1996. Holden had his own glimpse: the back of the creature as it slowly moved away.

Sceptics suggest sun bears, gibbons, siamangs or juvenile orangutans. Overlapping or rain-worn sun bear tracks can resemble a short, broad, human-like foot. Folklore and expectation may shape what people see. Supporters answer that a standing bear is snouty and unsteady. Primatologist David Chivers called the footprints distinct from all these species.

Hair from later expeditions has not settled it. Hans Brunner reportedly identified one sample as an undocumented primate species. Others came back as golden cat or tapir, and a 2014 genetic study by Sykes and colleagues matched one Sumatran hair to a Malayan tapir.

Richard Freeman and the Centre for Fortean Zoology followed Martyr into the Sumatran forests. Theories range from an unknown ape to a surviving relative of Homo floresiensis. No photograph. No body. Just one journalist, one valley, and a camera that never took the picture.