Wesley and Mark attempt to hold-up a convenience store at a gas station. The cashier, an elderly lady who suffers from heart disease, collapses gasping and panting when Wesley points a water pistol at her and Mark menacingly demands all the money in the cash register. Wesley and Mark run away from the scene empty handed. The cashier goes into shock, and dies shortly afterwards. Wesley and Mark were arrested and charged with murder.

Discuss the criminal responsibility of Mark and Wesley.