Inquisitor Gregor Eisenhorn found himself on the trail of the Necroteuch whilst investigating House Glaw and in particular Pontius Glaw. Pontius and his associates were of the belief that the Necroteuch would have power enough to raise his consciousness from the crystal it was entrapped in and create a new body. Further plans were unknown, although with such a powerful artifact it is unlikely that he would have stopped there.
The Necroteuch was originally believed destroyed, as were all copies in known human space. However, an alien species called the Saruthi had acquired a copy in ages past, a copy which seeped into the unique physiology and psychology of this alien civilisation, warping it thoroughly. House Glaw felt that they could trade Saruthi artifacts for the copy of the Necroteuch and were only stopped by the combined efforts of Eisenhorn, his retinue and loyal Imperial Guard troops.
During the fight Eisenhorn managed to gain possession of the book, although in doing so he was briefly exposed to its insidious influences and almost fell under its spell. However, the Chaos Space Marine Mandragore attacked, forcing Eisenhorn to react and breaking his trance. Eisenhorn fought bravely but was bested the Chaos Space Marine. Desperate, he tricked Mandragore in picking up the Necroteuch. Mandragore bend down laughing, but as he touched the Necroteuch, its massive aura forced him into trance as well. Eisenhorn beheaded him, causing his physical form to spontaneously combust. It was into this pyre that he put the Necroteuch, lest it tempt him further.
This was not the end of the Necroteuch however, as the Saruthi had created a copy of their own which the remainder of House Glaw were intent upon capturing. A combined attack by Imperial Guard and Space Marine forces with support from the Imperial Navy and including several Inquisitorial strike teams managed to destroy this copy at a high cost. This attack was also the first time Eisenhorn came face to face with the daemonhost Cherubael.