This is also a good opportunity to review the relevant Alaska statute. Some of the commentors are getting mixed up in the whole "defense of property" thing. To be clear, Alaska law does not allow you to use lethal force in defense of property. In general, to use lethal force in self defense, you must comply with "AS 11.81.335. Justification: Use of Deadly Force in Defense of Self."
- (a) Except as provided in (b) of this section, a person who is justified in using nondeadly force in self-defense under AS 11.81.330 may use deadly force in self-defense upon another person when and to the extent the person reasonably believes the use of deadly force is necessary for self-defense against
- (1) death;
- (2) serious physical injury;
- (3) kidnapping, except for what is described as custodial interference in the first degree in AS 11.41.320;
- (4) sexual assault in the first degree;
- (5) sexual assault in the second degree;
- (6) sexual abuse of a minor in the first degree; or
- (6) robbery in any degree.
- (b) A person may not use deadly force under this section if the person knows that, with complete personal safety and with complete safety as to others being defended, the person can avoid the necessity of using deadly force by leaving the area of the encounter,, except there is no duty to leave the area if the person is
- (1) on premises
- (A) that the person owns or leases;
- (B) where the person resides, temporarily or permanently; or
- (C) as a guest or express or implied agent of the owner, lessor, or resident;
- (2) a peace officer acting within the scope and authority of the officer's employment or a person assisting a peace officer under AS 11.81.380;
- (3) in a building where the person works in the ordinary course of the person's employment; or
- (4) protecting a child or a member of the person's household.
First, you have to be justified in using non-deadly force. In general, as long as you don't initiate or escalate a conflict, you may use force to respond to another's unlawful use of force. The general legal requirements for deadly force are ability, opportunity, and jeopardy. Those requirements are spelled out in the above statute, which only allows you to use deadly force against the threat of death or serious bodily injury, robbery, and some other crimes.
I think this homeowner -- who was bludgeoned -- is justified under both the robbery and threat of serious bodily injury requirements. Note that robbery is not theft; robbery is a crime against the person, as well, as it implies a threat of force.
The only thing our castle doctrine law does is remove the duty to retreat when on your own property or defending your family. Note that generally, you cannot use deadly force to protect property.