Dr. Theodor Bohmer was the mentor of a young Ludwig Frankenstein in Visaria. It was Dr. Bohmer who performed the first recorded brain transplant, although thanks to slight error the entire procedure ended in failure. Not content with just being the one to "blaze the trail," as Ludwig put it, Bohmer grew increasingly jealous of his student when Ludwig repeated the older scientist's experiment and succeeded where Bohmer had failed. Regardless, Bohmer came to work alongside Ludwig when the younger man started his own brain treatment clinic in Visaria.
Bohmer's chance for greatness came with the arrival of Ygor and the Frankenstein monster. He just didn't know it at first. Ludwig planned to replace the monster's defective brain with that of the recently deceased Dr. Kettering, but Ygor had other ideas. The twisted old man persuaded Bohmer to secretly put his brain into the monster in lieu of Kettering's, and in return Bohmer would have anything he wanted. Bohmer agreed and removed Ygor's brain, passing it off as Kettering's and then giving it to Ludwig who performed the operation. Unfortunately for everyone involved, the operation was a massive failure. Ygor blamed Bohmer for the disaster, and the evil scientist was flung violently into some electrical equipment and electrocuted to death.