The Manhunters were observing events unfolding on Krypton involving Jor-El and Lara. The Manhunters wanted to intercept Kal-El's Spacecraft before it reached its destination of Earth. The Manhunters wanted to make Kal-El a Manhunter agent, but they were stopped by the Guardians of the Universe and the Green Lantern Corps.
Two Manhunter robots arrived at the residence of Dr. G. I. Whitney and his wife. The Manhunters were a splitting image of the real Dr. Whitney and his wife. The real Dr. Whitney was killed along with his wife. Afterwards, both Manhunters assume the identities of the human doctor and his wife. The Manhunter doctor delivered and cared for the babies of Smallville for over 30 years. After some time the female Manhunter impersonating Dr. Whitney's wife "was programmed to die" and Dr. Whitney was to show signs of aging as humans do. The goal of the Manhunters was to implant all the children with a "microscoptic inducer" which would make the residents sleeper agents for the Manhunters. Two such sleeper agents were Pete Ross and Lana Lang.