Crozier was born after 2339 (PROSE: Mindwarp) and, at an unusually young age, became a doctor and a scientist. (TV: Mindwarp) By his late thirties, he had a daughter named Cordelia, who followed in his footsteps and became a scientist herself. (AUDIO: Antidote to Oblivion)
Crozier was summoned to Thoros-Beta to help Lord Kiv in 2379 in return for funding for his work, also being threatened with death should he be unsuccessful in saving the Mentor's life. He was assisted by Kiv's most trusted servant, the Matrona. In his attempts to discover how to transfer Kiv's mind into another body, he experimented upon the Raak, making it docile against its nature. He also attempted to alter Yrcanos's mind to the financial benefit of the Mentors.
When the Sixth Doctor arrived on Thoros-Beta, Crozier subjected him to the helmet to interrogate him. This affected the Doctor's personality and seemingly made him sympathetic to the Mentors, becoming Crozier's assistant. Crozier seemed to successfully transfer Kiv's mind into Peri Brown's body, after which Yrcanos killed both her (TV: Mindwarp) and Crozier. (PROSE: Mindwarp)
Due to the Time Lords, multiple timelines existed, (AUDIO: Peri and the Piscon Paradox) including one in which the transfer was a failure and Crozier was killed by Sil, who lied to Cordelia and told her that the Doctor was to blame. (AUDIO: Antidote to Oblivion) In at least one timeline, Crozier's mind transference failed because his earlier interrogation of the Doctor had allowed Mandrake to escape the Doctor's mind and enter Crozier's computer, and from there it was Mandrake's consciousness that was transferred to Peri's body, overwriting that of Kiv's. (AUDIO: The Widow's Assassin)
Crozier devoted his life to perfecting the control and manipulation of behaviour. His manner was abrupt and showed a dismissal of anything and everything aside from his scientific passions, which included his fixation upon his study of the brains of creatures that possessed or could be given the power of reason. He held contempt for those that he deemed to be barbarians, including the Krontep. (PROSE: Mindwarp)
Behind the Scenes
Nicholas Ball, Andrew Burt, Michael Cochrane, Phil Collins, Peter Firth, Jack Galloway, Clive Merrison, Jeff Rawle, Simon Rouse, Paul Shelley, David Warner, James Warwick and Simon Williams before Patrick Ryecart was cast.