Rajesh Singh was a researcher and lab doctor at the Torchwood Institute.
During 2005 and 2006, he worked closely alongside Yvonne Hartman and Ianto Jones in Hartman's investigation of the contents of the sphere. On 26 March 2005, Singh worked overtime to help Hartman during her investigation of alien murders in Cardiff. He fell asleep at his desk whilst waiting for Hartman to call back and was woken by Jones. (AUDIO: One Rule)
In July 2007, he was stationed at Torchwood 1, and had the task of ascertaining the Void Ship's purpose, but couldn't, because according to all available instruments, the "Sphere" didn't exist. He, along with every member of Torchwood, had undergone and passed psychic training. He wasn't affected by the psychic paper's low-level telepathic field, foiling Rose's attempt to gather information. When the Cult of Skaro emerged from the Void Ship, he claimed personal responsibility for allowing it to happen and volunteered himself as the least important person present. Dalek Sec ordered him to kneel and requested information about current Earth history. Singh responded saying that he would comply but not compromise Homeland Security. Sec interrupted, revealing that speech was not required; instead, they will extracted his brainwaves by placing their manipulator arms around his head. Singh screamed in agony. As the Daleks let go of Singh, his desiccated corpse fell down to the floor before them, much to Mickey and Rose's dismay. (TV: Army of Ghosts/Doomsday)
Rajesh Singh was intelligent and generally pleasant, a very brave and selfless man. He was direct and task-oriented. He seemed more annoyed by Rose's infiltration than concerned, (TV: Army of Ghosts) though when the Void Ship opened and war broke out on a worldwide scale, he realised the true gravity of what Torchwood had been doing. (TV: Doomsday)