There is local precedent to help the prosecutor reach a decision in the Gail Gerlach/Brendon Kaluza-Graham incident. In 1992, Michael Afana tricked Roger Vick into breaking into his home. He armed himself and waited in ambush. He surprised Vick in the act of a burglary and shot him in the head as he went down the street to get away. Vick survived and Afana was arrested for first-degree assault. As reported in the local media, Prosecutor Don Brockett declined to prosecute Afana, basing the decision on what was termed a “little-used state law.”
Perhaps law-abiding citizens, and criminals, should be more aware of that law. RCW 9A.16.020 reads, in relevant part, “The use, attempt, or offer to use force upon or toward the person of another is not unlawful in the following cases: (2) Whenever necessarily used by a person arresting one who has committed a felony and delivering him or her to a public officer competent to receive him or her into custody.”
Stealing a car is a felony. The law allows citizens to arrest people who commit felonies, and to use force when necessary to do so. Committing felonies is a risky hobby. No felony, no shooting.