Dr. Van Criss was a scientist, founder of Van Chris Laboratories.
Van Criss's Van Chris Laboratories was a subsidy of Wayne Enterprises, specialized in developing nanotech, which was used in Amanda Waller's neck implanted bombs in Task Force X. Leaning this from torturing Griggs, Joker staged a raid on the facility, killing numerous guards and forcing Van Criss to work for him after kidnapping his wife.
Van Criss was present when the Joker rescued Harley Quinn, disabling her neck bomb so Rick Flagg could not kill her. He ultimately died when Waller shot down the helicopter he was on.