Arthur Linwood

Arthur Linwood was a medical student in his final year when he observed the first use of the Keller Machine in Stangmoor Prison, where he met James Stevens, who was also an observer. (PROSE: Who Killed Kennedy)

Shortly afterwards, Linwood became the first victim of the machine when it killed him by turning his fear of rats against him. His fear was so great that rat bites and scratches manifested on his face and neck. (TV: The Mind of Evil)

Behind the scenes
Interestingly, the novel Who Killed Kennedy accidentally depicted the same person present at the Keller observation as James Stevens and Arthur Linwood. In the novel, it is described that James eavesdrops on the conversation after the meeting by "studying" the Keller machine. In actuality, it is Linwood who studies the machine within the episode, although his character went unnamed until the publishing of Who Killed Kennedy.