Dr. Klein was a Terran Dominion scientist who headed the Metis xeno-research facility on Korhal IV during the Second Great War. During Kerrigan's invasion of Korhal in 2505, Abathur took notice of the facility and decided to use it as a testing ground for a new strain of ultralisk. Kerrigan telepathically called out to a captive ultralisk, causing it to break loose and rampage through the facility, freeing the other captive ultralisks. During the escape, a pair of canisters broke open, exposing the ultralisks to toxic gas. Abathur integrated the toxins into the ultralisks' essence, mutating them into the Noxious-strain. As the Noxious ultralisks continued their rampage, a panic-stricken Dr. Klein frantically yelled at the guards to kill the zerg, warning them that the Emperor would have their heads if they failed. Ultimately, the Dominion troops proved no match for the Noxious ultralisks, which broke out of the lab and crippled the facility.