Leitz was a member of the Federation personnel on Helotrix. He was the right hand man of Servalan in her guise as Commissioner Sleer. He was also assigned to the incoming president Practor as a liaison officer. Practor identified a painting of Servalan to him. Leitz aided Servalan in her dealings with Forbus over the production of pylene-50, earning the scientist's hatred as they used the drug to subjugate the population.
Leitz had also been ordered by Servalan to infiltrate the resistance, pretending to feed them information while in fact leading them into traps. His information led to the destruction of their second column. He met Hunda, the leader of the fourth column and the only one still operational, along with Tarrant and Dayna. On learning Hunda was planning a raid on the city to destroy the Federation's communications terminal and command centre, Leitz suggested he could get into the city through the old monorail. He also told Tarrant and Dayna the location of the pylene-50 processing plant but failed to tell them about a booby-trapped key card which he assumed would kill them.
After discovering Practor had been murdered, Leitz informed the General of his activities with the resistance and advise him to fill the tunnel with explosives and blow it up when they used it. However, Tarrant and Dayna had discovered his treachery, and not only warned Hunda and his men but provided them with a vaccine against pylene-50, making them immune to the Federation's medical lasers. Leitz accompanied the Federation troops who went to fight off a rebel attack on the concourse, but like Servalan, he quickly slipped away from the battle when it became clear the rebels had the upper hand.
Leitz arrived at the processing centre just after Servalan had killed Forbus and offered to testify that it was self-defence. He told her that he knew of her identity and that she had killed Practor to hide it, asking for the presidency in return for his silence. As they embraced, Servalan casually killed him. (D: Traitor)