The forensics, at least, are clear. Comparing satellite images, investigators pinned the creation to a narrow window: on 27 May 1998, a NASA Landsat-5 pass showed the plateau undisturbed; by 12 June, the completed figure was there. Whoever did this carved lines up to 35 metres wide and shifted earth across kilometres of terrain - work that experts concluded required an earthmoving machine and an expert grasp of satellite-guided positioning, then a cutting-edge and barely available technology. The audacity is staggering. Someone moved heavy equipment into remote country, executed a drawing the size of a city, and vanished without leaving a single eyewitness behind. The desert kept the secret completely. In a modern world saturated with cameras and records, the Marree Man is a genuine mystery: a monumental act of creation with no confirmed author.

The clues that did surface only deepened the puzzle - and may have been designed to mislead. A series of anonymous faxes arrived at media outlets and local businesses, dubbing the figure 'Stuart's Giant' after the explorer John McDouall Stuart. Their wording was conspicuously un-Australian: references to 'your State of SA', the 'Queensland Barrier Reef', and a nod to Ohio's Great Serpent Mound, an earthwork few outside the United States would know. A glass jar was reportedly unearthed at the site holding a satellite photo and a note bearing a U.S. flag. Later, a fax described a buried plaque stamped with the American flag and the Olympic rings. It all pointed across the Pacific - which is precisely why some suspected the American flavour was theatre, planted to throw investigators off an Australian trail. One name that surfaced was Bardius Goldberg, an Alice Springs artist with a taste for the grand gesture, the know-how, and access to machinery. Goldberg never confirmed it, and he took whatever he knew to his grave in 2002.

For all the public delight at the riddle, the Marree Man raised a harder question that the headlines often skipped. The figure depicts an Aboriginal man hunting - rendered, it later emerged, after photographs in a 1946 book describing hunters of the Pitjantjatjara language group - yet it was bulldozed onto country sacred to others, by an outsider who never asked. At the time, the land was the subject of a native title dispute between the Arabana and Dieri Mitha peoples. The Dieri Mitha spoke out against what they saw as harm to and exploitation of their Dreaming, calling for the image to be erased and its maker held to account. Their objection cuts to something real: a stranger had seized the likeness of Aboriginal identity and carved it across Aboriginal land as a spectacle, without consent or consultation. Officials condemned the work too - the state environment minister called it vandalism. In 2012, the Federal Court recognised the Arabana people as the land's traditional owners.

Deserts erase things, and the Marree Man began to dissolve almost at once, its lines softening year by year under wind and the rare rain. By 2016 the figure had nearly vanished back into the plateau. Then, with the consent of the Arabana Aboriginal Corporation, a group of locals decided not to let the giant disappear. Using a commercial grader steered by GPS, they spent some sixty hours re-cutting the entire outline, matching the original so precisely that it underscored an irony two decades in the making: a figure that could scarcely have been created without GPS in the first place. The Marree Man strides again across his plateau, sharp enough to see from a passing plane. He remains exactly what he was on the day a startled pilot first spotted him - vast, silent, and unclaimed. The land beneath him has its rightful owners. The figure above it still belongs to no one.