In early 2003, an exceptionally gifted psychic medium named Johann Kraus was hosting a séance for a small group. While he was partially on the ethereal plane, the Chengdou disaster struck. No one knows the specifics, but it involved an ancient terra cotta statuette in the care of the Chinese government. The result was essentially a psychic Chernobyl. Everyone within a hundred miles of the disaster itself had their souls "consumed", reducing them to mindless husks. On the ethereal plane, however, the disaster was much greater; everyone not physically in their body within three thousand miles of the incident was instantly incinerated.
The only survivor was Krauss, and some would argue that he died as well. His ectoplasmic form survived when his body was incinerated, and knowing he would soon dissipate without a physical body, he sought out the best paranormal minds on the planet for help - the B.P.R.D.. At first he persisted in a bizarre transparent tank apparatus developed by the B.P.R.D for other purposes, and eventually the technology was sized down into the distinctive containment suit. Kate Corrigan has said of him that, "He's not dead. He just doesn't have a body anymore."
After the loss of
Hellboy, Krauss was hired to replenish the Bureau's pool of 'enhanced talents'. Krauss soon proved an invaluable member of the team. His talents are better than ever, a situation similar to a musician who has lost his eyesight. Where once he could speak with the dead, now he can give them temporary physical form. He no longer requires rest. He works constantly and is, as of the Garden of Souls storyline, researching the files culled from the sub-basement of the Bureau's Colorado mountain base.