Roberts fulfilled but did not extend his six-year contract for "Bonanza", and when he left the series, his character was eliminated with the explanation that Adam had "moved away." Later episodes suggested variously that Adam was "at sea", had moved to Europe, or was on the East Coast, running that end of the family business. The last episode Pernell Roberts worked on was "Dead and Gone", air date April 4, 1965. He appeared in the next two that aired which were filmed prior to "Dead and Gone" — "A Good Night's Rest", air date April 11, 1965, and "To Own The World", air date April 18, 1965. Adam Cartwright was mentioned on occasion in the series (including a 1967 episode which did not air until April 4, 1971 ("Kingdom of Fear"). In television interviews, Roberts said that he would have stayed with "Bonanza", had he been allowed to do so on a part-time basis to enable him to return to theater. Bonanza producer David Dortort described Roberts as "rebellious, outspoken... and aloof," but, as one who "could make any scene he was in better...". In a later archive interview, he regretted not having insisted on a "marriage for Adam" and having Roberts continue on the show as a semiregular. He added, "I must confess..I was too hard on him. I did not appreciate him. I knew he was good, but I didn't realize he was that good...none better." In the last two "Bonanza" movies that aired on NBC in the early 1990s, the story line stated that Adam, now in Australia, had equaled his father's success, dominating the engineering/construction business.