I don't feel a need to judge all of these cases and I would not try to do so on the basis of newspaper accounts. The Grand Jury testimony is sealed. But you can probably get the police report.
Often if someone has died, the DA will not feel that they can just decline to prosecute. So they will send it to the Grand Jury. As is always said though, "The Grand Jury would indict a ham sandwich." Prosecutors usually have these grand juries right in their pockets.
If the prosecutor does not want an indictment they usually have ways they can communicate this to the Grand Jury. So if the DA does not want an indictment I am not going to second guess them. That is their responsibility. If you wanted more info, the next step could be the case file and police report.
Usually someone who acts in the immediate self defense of themselves or another, they are not called a vigilante. Like in that Greenwood Indiana shopping mall shooting Police are calling the armed civilian a Good Samaritan.
SJG
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