Dr. Teng was one of the scientists responsible for creating Bizarro.
History
When the first public clone of Superman started to malfunction, Teng proposed to Luthor that they scrap the project, but Luthor would not hear of it.
At Luthor's request, Teng studied the creature. "Bizarro", as the malfunctioning specimen had become known, did not take kindly to Luthor's remark that he was a glitch, and attacked. After Teng sedated him, Luthor ordered the doctor to scrap the project anyway. Teng initiated the lab's self-destruct, but their getaway was hindered by Bizarro. After the real Superman showed up and unblocked the doors, Teng escaped in the helicopter with Luthor and Mercy.