Dill was from Alabama. At school, he was nicknamed "Dill the Pill" because he was rather hard to take, a comment on his personality and habit of speaking without thinking. (PROSE: The Chase) He saw a number of illusions performed, including long police cars coming out of small wooden sheds.
In 1966, Dill visited New York City as a tourist. Whilst on the Empire State Building's observation deck, he encountered the First Doctor, his companions Ian Chesterton, Barbara Wright and Vicki Pallister and a Dalek. He assumed they were all actors and, as they were not seen by anybody else, his behaviour seemed very odd, prompting the tour guide to fetch a policeman and ask another tourist to ensure he did not jump, calling him a "nutter". (TV: The Chase)
After explaining what had happened to two guards, he was locked up at the Newman Rehabilitation Clinic in 1967, where he became a permanent resident. The Dalek he had met had decided that such a life would be far worse a fate than killing him. (PROSE: The Chase)