Around this time he joined the movement that was to become Scientology leaving KTLA to become an editorial/personal assistant to founder L. Ron Hubbard.
"[2]: 31 On February 24, 1951, De Mille assisted Hubbard in kidnapping the latter's wife, Sara, from her apartment in Los Angeles in an unsuccessful bid to have her declared insane by a psychiatrist.
By 1954, however, he had become disillusioned with Scientology and left the organization, explaining that he "didn't like all the contradictions and I was becoming more and more sceptical of the whole thing".
He remained with that institution as a research psychologist until 1962, when he became a lecturer in psychology at the University of California, Santa Barbara.
[6][7] He edited a second book on the same subject, The Don Juan Papers in 1980, when he found that his exposé did not lead Castaneda's most ardent followers to fall away.