A Missouri man accused of murdering his ex-girlfriend allegedly made her watch him dig her grave before killing her, said authorities. Tony L. Charboneau, 36, has been charged with first-degree murder, domestic assault, kidnapping, abandonment of a corpse, tampering with physical evidence, and conspiracy to commit kidnapping, in connection with the death of Amy Hogue, 43, according to the Washington County Prosecutor’s Office. Co-conspirator and current girlfriend, Brandi L. Luffy, faces similar charges for her alleged involvement. On June 20, Charboneau allegedly beat Hogue following an argum…