Defending Your Neighbor's Home with Lethal Force

Undoubtedly many of you have heard about the 61 year old Pasadena, Texas man who smoked two burglars as they came out of his neighbors house last week. 
 
Mr. Horn, the shooter, called 911 just after 2 PM after the suspects broke into his next door neighbor's window.  The Houston Chronicle has the entire recording of the 911 call [here], including the firing of the shotgun and the aftermath as the police showed up.
 
There is some controversy over Mr. Horn's involvement, most notably whether he had the right to intervene in the burglary of his neighbors property (without their explicit permission). 
 
On September 1st the "Castle Doctrine" went into effect in Texas which declares that individuals can use lethal force to protect their home, property and vehicle from burglary, arson and other criminal mischief.  In this incident the criminals burglarized Mr. Horn's neighbor's home. 
 
Mr. Horn does, however, claim that he went out to tell them to stop and the criminals then entered his yard (whilst he was armed with his shotgun) and that's when he fired his shotgun three times.  Note, though, that Texas does not have a "Duty to Retreat" clause for its "Castle Doctrine".
 
Both criminals died as a result of the gun shot wounds inflicted by Mr. Horn.
 
Even in the case of Texas' Concealed Handgun Laws this entire scenario would be blurry in the eyes of the law.  As with the CHL, Mr. Horn will have to contend that he was in fear for his life when he stopped the criminals with his shotgun.  Unfortunately, in the rather lengthy conversation with the 911 operator, Mr. Horn makes it clear that if the police don't arrive before the suspects leave he will take matters into his own hands.   
 
Mr. Horn was not arrested or charged by the Pasadena Police Department in this incident, although the case has been referred to the Harris County Grand Jury. 
 
Personally I hope a precedent is set here whereby the grand jury no-bills Mr. Horn.  A clear message will be sent to all the criminals in Texas that their behavior will not be tolerated.  
 
What do you think?

 
Resources:
Houston Chronicle Story (with 911 Call)
The Castle Doctrine (overview)
Concealed Handgun Laws (overview)