The original Mk1 zombies were an accident created by a Jutonian scientist within the LIMITATION Facility. The scientist was working on an engineered virus able to adapt to find the various forms of cancer in order to seek out and cure them. As a result, the virus had to be able to vary itself drastically to combat different causes of cancer. Unfortunantely, the last prototype of the cure turned out to create random zombies with adaptive potential.
The security forces within the LIMITATION Facility were able to combat the zombies with the assistance of Auto-Turrets. The zombies were unable to adapt quickly to the simple weaponary used at the time, and were promptly wiped out.
The Mk2 Zombies were created near the end of Juton's efforts to produce a cure for cancer. Though Juton stayed away from the original characteristics that ended up creating the Mk1 zombies, the Mk2 zombies resulted anyway. George Wilkins was present in the LIMITATION facility at the time, and engaged the zombies in combat. Almost every soldier outside of George's squad was eliminated by the deadly zombies, prompting George to seek help from experimental weaponary and armor within the facility.
The Smart Zombies had disabled auto-turrets and surveilance equipment within the afflicted area, so the squad had no idea what to expect when they entered, however George was not with them. He was busy outfitting himself with prototype IWD armor. Utilizing a mech, a plasma rifle, and other experimental equipment, the squad managed to take out large numbers of hostiles, before falling to the zombies that were extremely agile. The squad commander survived long enough to explain to George what had happened.
George tore apart the zombies with the IWD armor, but was forced to retreat since his armor lacked EFB/IC fields. The massive acceleration from the attacks of the larger zombies would end up killing him without the fields. After battling zombie after zombie, George was eventually forced to activate the self-destruct within the facility, instantly vaporizing the zombies, equipment, and people within. George managed to exit just in time, but the acceleration caused by the impact of the explosion killed George.
Unfortunantely, three super-tough spores from the facility escaped into space. Juton detected one, and the Ottoman Empire detected another. The third spore however, went completely undetected.