Partner of Dr. Richard Flemming at Immunitech Research. The two men were likely paid by the N.I.D. to develop a means to clone Adrian Conrad's Goa'uld symbiote. Stoeffer and Flemming ordered all of the latest information on stem cell research to help them with their work. After successfully cloning dozens of copies of the symbiote they were able to formulate a drug that would suppress the Goa'uld's control on the human host, as well as kill it.
After their research was complete Stoeffer fell off the map. No trace of him was ever found. Two months later his partner, Flemming, disappeared after a car crash. The Goa'uld were likely responsible for both disappearances.
Nightwalkers - Sheriff Knox tells Major Carter of the unexplained disappearance of Dr. Stoeffer.