Jurors delivered the guilty verdict late Friday afternoon after less than two days of deliberations.
During the five-day trial, three witnesses testified they saw 50-year-old Shepherd shoot Miller after an argument.
Shepherd, testifying in his own defense, argued that his life was in danger.
“I tried to keep [Miller] from shooting me,” Shepherd said on the stand. “We were both struggling and I tried to twist it so [Miller] could drop the gun, but the gun went off.”
In addition to murder, jurors also found Shepherd guilty of five related weapons and destruction of property charges.
Judge Russell Canan scheduled a sentencing hearing for Oct. 3 at 11 a.m.