Once a noted geneticist, Dr. Emile Dorian once worked closely with Dr. Kirk Langstrom. His goal was to create chemically-induced mutations that would alter the genetic structure of living things, using a compound he invented called T-99. Because Dorian was obsessed with cats ("Their power, their grace, their beauty."), most of his experiments involved turning other animals into cat-like creatures. In fact, his first attempt at altering human genetic structure, Garth the gorilla-man, is thought to be his only non-feline experiment.
Independantly wealthy, Dorian lived on an island off the coast of Gotham City, which teemed with cat-monkeys, cat-birds, cat-lizards, and other cat-things that were the results of Dorian's work. He retired there after people began protesting genetic engineering and, studying privately, was able to create Tygrus, a panther-man, "from scratch, so to speak." Calling Tygrus the pinnacle of his art, he sought to create a mate for him, and thus sent Garth to Gotham City to abduct Selina Kyle, alias Catwoman.
Using his serum, Dorian turned Selina into a literal cat-woman. When Batman came to rescue her, Dorian gave the Dark Knight a chance to restore Selina's humanity: if he could defeat Tygrus, Dorian would give up the antidote to Selina's mutation. But even as Tygrus pursued Batman through the jungles of the island, Dorian prepared to give Selina the final shot to make her mutation permanent. She escaped however, and was able to turn Tygrus against his "father" by convincing him that Dorian was an evil man.
Tygrus attacked Dorian in his laboratory, on the grounds that Dorian had always wanted Tygrus to be utterly ruthless killer and he was just doing what his "father" wanted. When the laboratory was destroyed however, Tygrus could not let Dorian die, saving his creator from the fire. The injured and unconscious Dorian was then relinquished to Batman's custody, and since Tygrus request that Batman "get him help," it can be assumed that Dorian sought psychiatric treatment at Arkham Asylum.
Although never explicitly stated, it is thought that the work Dorian did is what led to the splicing phenomenon in mid-21st-century Gotham.