Supposedly, he hypothesised that white noise was telepathic communication from the dead; when he ran the noise through a translation matrix of his own design, he heard three words: "don't cremate me". Convinced that the dead continued to feel what happened to their bodies, he created 3W to care for the deceased. The Twelfth Doctor called him an idiot. (TV: Death in Heaven)
In fact, Skarosa was a pawn in Missy's plan to convert the dead into a Cyberman army. She had, after killing all the members of the Scoundrels Club, paralysed him and pushed him into a fire. (PROSE: Dismemberment) Skarosa eventually died and was laid to rest at the 3W facility inside St Paul's Cathedral.
Like the others entombed by 3W, he underwent Cyber-conversion. When Missy commanded "bring out your dead", (TV: Dark Water) Skarosa became active and was released from his chamber. He encountered Clara Oswald who, playing for time, insisted that she was, in fact, the Doctor. Skarosa regrouped with more Cybermen to confirm Clara's identity. One of those other Cybermen was an emotionally intact Danny Pink, who stunned Clara and destroyed Skarosa and the other Cybermen. (TV: Death in Heaven)