Thomas Vaughan was a Hermetic philosopher and scientist in 17th century Wales, who published several alchemical texts under the name "Eugenius Philalethes". After discovering the secret of immortality, he faked his death, placing his unpublished alchemical studies in his crypt. He later founded the Arcanis Servitorus to protect his secret.
In the early 21st century, Vaughan was posing as Sir Robert Craig, a billionaire businessman and philanthropist, and was the head of the CARU Clinic, which he used to find a cure for his son's condition. An archaeological team unearthed Vaughan's crypt, and one of its members, Alice Proctor, discovered the truth about Vaughan, and told her employee, Sir Giles Walbridge, and her friend Jack Harkness. When Walbridge tried to blackmail Craig, he had Walbridge and his team killed. Jack investigated Proctor's death, and upon learning that Craig was responsible, killed him by forcing him to crash his car. Jack was arrested for the murders of Craig, Proctor, and the other people killed, but was cleared of all charges thanks to the Torchwood Three team, who had conducted their own investigation and uncovered the truth about Craig. (AUDIO: Hidden)