A 41-year-old Billings man has denied a deliberate homicide charge filed after the shooting death of his girlfriend's lover early on Christmas Day.
    
David Bruce Isaacson entered his plea Thursday in the death of 35-year-old Sabah Mallak, who was shot twice in the back.
    
Court records say Isaacson's girlfriend, Daniel Calhoun, told police she called Mallak to pick her up because she wanted to do meth and have sex.
    
Prosecutors say Isaacson told investigators he and Calhoun argued after he learned she had called Mallak.
    
Isaacson said when he saw Mallak's car pull up, he approached and Mallak drove the car at him. He said he shot at the driver's side window and the car crashed into a tree. Mallak stumbled out and Isaacson told officers he shot him again.