The training was intense and the few that survived infancy turned on each other. After the young assassins killed each other off, the only one left was Mad Dog. Ra's al Ghul sent one of his Ubu to dispose of the boy, but the servant took pity on Mad Dog and set him free into the wild.
This was unknown to both David Cain and Ra's al Ghul but was discovered by Ra's al Ghul's daughter, Nyssa Raatko. Mad Dog's breakdown convinced David Cain that the perfect weapon needed perfect genetics which is the beginning of his project that would lead to the eventual birth of Cassandra Cain.
Nyssa Raatko later reformed the league of the assassins along with Lady Shiva after the death of her father Ra's Al Ghul. The new League consisted of Mad Dog, Circle of Six and former members Alpha and Shrike. When Cassandra Cain now as Batgirl sought out Lady Shiva, she was forced to fight with the new League while Mad Dog sought to kill her.
Mad Dog went into a killing spree during which he killed all the League personal loyal to Cassandra Cain, except for one who Cassandra protected and died for after Mad Dog stabs her, as she knocks him unconscious.
- Martial Arts: He was trained by David Cain, along with several other members of the League of Assassins and a series of instructors hired by Cain.
- 7 Appearances of Mad Dog (New Earth)
- 1 Images featuring Mad Dog (New Earth)
- Quotations by or about Mad Dog (New Earth)
- Character Gallery: Mad Dog (New Earth)
League of Assassins member