The kill chip is a piece of Division technology that is implanted at the base of an agents cortex. When activate, it instantly kills the person and makes it look like a brain aneurysm. In 2007, Division first tried it on a North Korean official in order to cripple their nuclear program. By 2011, the kill chip was successfully hybridized with their trackers, to prevent any agent from going off the rails. This was tech was later evolved to the nanotoxin, invented by The Shop scientists, making the kill chip obsolete.
In "Intersection" Birkhoff had the task of removing Sonya's kill chip. The procedure was carried out in sub level twelve and took a total time of three hours.