At the 2012 Summer Olympics in London, Ziegler swam in the fastest qualifying heat of 800-meter freestyle and posted a time of 8:37.38, behind Rebecca Adlington of the United Kingdom and Lauren Boyle of New Zealand. Only the top eight swimmers of all five qualifying heats advanced to the 800-meter finals (with 8:27.15 as the slowest times of those eight), and Ziegler did not advance.