Page "Lex Luthor" Paragraph 37

Alexander Luthor, Jr. ( the son of Earth-Three's version of Luthor ) returned to the DC Universe along with other survivors from Crisis on Infinite Earths as part of a scheme to create a perfect Earth, under the pretense of restoring Earth-Two.

To this end, he assumed Luthor's identity and created a new Secret Society of Super Villains.

In response, the real Luthor took on the identity of Mockingbird and formed the third incarnation of the Secret Six in order to counter Alexander's organization.