There are a number of mysteries and enticing clues surrounding the disappearance of George Mallory and Sandy Irvine on the slopes of Everest in 1924. Paramount among the mysteries is of course whether they made it to the summit of the world's tallest mountain or not. It's a mystery that may never be solved and which is subject to endless conjecture and theory.

Other clues, tantalizing but inconclusive, have also been found. Among them is an oxygen bottle spotted in 1991 at an estimated 27,060 feet, apparently near the location where the ice axe was found in 1933. The bottle was found near the First Step indicating that Mallory and Irvine at least made it to the first of three steps. Unfortunately this sheds no certain light on the controversy of whether Mallory and Irvine may have climbed the more difficult Second Step as Odell believed he had seen them do.

The oxygen bottles were very old and were seen tucked under a rocky outcropping about 150 yards from the base of the First Step by Eric Simonson. When Simonson led the 1999 Mallory and Irvine Research Expedition back up the mountain his team recovered a bottle from a ledge in that area. From the shape of the bottle it could only have been from the 1920s and from its location it could only have been from Mallory and Irvine's climb. Given that the oxygen bottle was wedged into the rocks it clearly had not fallen and would indicate that one of the men, at least, had stopped on this spot to rest and change to a fresh bottle.

This would indicate, in theory, that the men were in fact still climbing strongly as Odell had claimed when he had last seen them. Indeed when expedition member Andy Politz stood on the spot where Odell claimed to have been when he made his sighting in 1924, Politz says he could easily see each of the three steps distinctly and thought there was little chance of mistaking one step for the other. From Odell's description Politz thought that the men could only have been climbing the Third Step when last seen.