19 BBY-21 ABY
During the end of the Clone Wars, the trooper crash landed on the desert planet, Du Mai, piloting his ARC-170 starfighter. When he crashed, he suffered head trauma and amnesia. Despite this, he retained small bits of his Kaminoan flash training. He took refuge in a mountain cave, where people would visit him. They mistook his displays of mental agitation and gnomic utterances as psychic powers. Villagers and pilgrims would travel to see him, while he uttered his incoherent military advice.
In 21 ABY, years after the trooper who the people had named Lost Prophet had died, journalist Cindel Towani had interviewed several of the local people and learned of the legend of Lost Prophet. She quickly realized that he was a clone trooper and that his wisdom was a part of the Kaminoan conditioning and training.