Post was a drug dealer serving life living in Unit B and working in the kitchen. Jefferson Keane told him to kill Dino Ortolani for him, and Ryan O'Reilly agreed to have Post transferred to the AIDS ward so he can get closer to Ortolani. Post spoke to Ortolani a few times and waited for the right moment. When Dino was put into the Hole and knocked unconscious, Post bribed a guard to let him in, and then he poured lighter fluid all over Ortolani and set him ablaze.
[Episode 01: "The Routine"]

The murder investigation of Ortolani was strong. Joey D'Angelo replaced Dino as the boss of the kitchen, and Post threatened to set him on fire also. The Sicilians discovered that Post had killed Ortolani, so he was tied up in a janitors' closet. Godfather Nino Schibetta tried to make Post tell who'd made him kill Ortolani, but Post just taunted him. Post was mutilated, his fingers cut off, and stabbed in the heart many times.
[Episode 02: "Visits, Conjecal or Otherwise"]