suspecting him of rustling cattle. When Snell disappeared in August 1918, and a search party found remains at a campfire in the ranges, Grindell was arrested and charged with Snell's murder. Despite the evidence being flimsy, Grindell was convicted at Port Augusta in December and sentenced to death, though it was later commuted to life imprisonment. He was released from prison in 1928, dying two years later at the age of 77. A restored building at the site of his old hut is now rented out as a holiday cottage. The bushman R. M. Williams is reputed to have learnt everything he knew about boot-making and leather from another man he met while camped in Italowie Gap at the southern end of the ranges; he later became a millionaire and a renowned clothing brand carries his name. The ranges were explored more thoroughly in the first half of the 20th century: the Greenwood family, pastoralists in the area, had explored the edges in the twenties and thirties, discovering Fern Chasm, but it was not until expeditions by Warren Bonython and others in the late 1940s that the Plateau and main central ranges were investigated and explored. On Bonython's first journey onto the Blue Range in 1946 several kilometres south of Benbonyathe Hill, one of his two companions, Bob Crocker, slipped and broke his leg, which resulted in Bonython walking more than twenty kilometres to Balcanoona station to organise a rescue effort: in the end Bob was carried off the high range by improvised stretcher in a seven-hour marathon. By 1948 the Plateau had been traversed in all directions, although the highest parts of the ranges are still out of limits for all but experienced bushwalkers. In the 1960s a group of American astronomers became interested in the higher peaks of the Gammons as possible sites for an observatory, and several parties camped for some time on the summits of Mount McKinlay and Benbonyathe Hill (vehicle tracks were also graded to the summits), but nothing further was done (a large observatory is located at Arkaroola, about a hundred kilometres to the northeast). Relics from these camps remain on the summits of the two hills, and there is reportedly still an overgrown vehicle track along the top of the Blue Range in places. A historic former mining site, the Bolla Bollana Brick Kiln and Copper Smelter Ruins, lies within the national park