From The TimeSplitters Wiki

Introduction

It is discovered in TimeSplitters: Future Perfect, that the zombies (at least the zombies in 1994) were actually created by Jacob Crow and The Brotherhood of Ultra Science, in his attempt to become immortal. Zombies, such as the shock zombies (which could fire electricity) in particular were early 'prototypes' for the TimeSplitters

The original author of Zombie does not have any further information on this article. The author may return to finish the article when information has been gathered, however they welcome anyone to expand on this article.