He was also the head of LuthorCorp's Nanotechnology Division.
First Works with Luthorcorp
Lex hired Dr. Groll to study and examine the Black Box. He informed Lex that the box was a power source that could provide energy or be used as an extremely destructive weapon. Lana feared that Lionel would undersell Lex and obtain Groll's information, so she approached Dr. Groll and casually suggested that if he chose to betray Lex, his job and family would be threatened. Dr. Groll later met with Lana, claiming he did not want anything else to do with the black box. He gave Lana all the information he had gathered. He promised never to disclose anything he learned and even warned Lana that Lex has already started military testing on the box. Dr. Groll and his family then went into hiding. This encounter was then photographed by Jimmy
Tess Mercer tracked Dr. Groll down while still in hiding to have him perform tests on the Crystal of Knowledge. He and his team then worked out that the crystal was some sort of alien computer hardrive and planned to open it using a high frequency test but when he performed it, it shot a beam of light into space bringing Maxima to earth.
Dr. Groll was working on Project Prometheus which was a suit designed to allow Lex Luthor to survive after the collapse of the Fortress of Solitude and at the same time grant him powers. Lana learned of this information and agreed with Dr Groll that Lex would corrupt its power and so they moved the Project to a safe location and Lana became the subject instead. Dr. Groll successfully fused the suit to Lana granting her powers just after Tess broke into the facility and tried to destroy the suit. She and Dr. Groll fought before she shot at him but Lana broke out and stopped the bullet knocking Tess out before leaving at super speed.