S1·E32 Death of a Cop

When policeman Philip Reardon is killed in drug bust, his police officer father feels responsible because his son joined the police force to follow in his father's footsteps. In order to set things right, Philip's father strives to brings his son's killers and their mob boss Herbie Lane to justice. The plan leads to his own death at the hands of the criminals, but in death he is able to fulfill his goal. Before the murder he had stationed a fellow officer nearby to witness the killing and bring the entire gang to justice.