[AnotherUnixGeek]

If they were not aware of his trespass, then how the f*** did they know to be chasing him? Clearly they were aware of it. Not being aware of it would have caused them to do nothing.

The killers didn't even claim to have witnessed any crime happening in their presence, nor were they aware of any felony having been committed. They had zero grounds for any citizens arrest, by Georgia law.

[DiogenesLamp]

The killers didn't even claim to have witnessed any crime happening in their presence, nor were they aware of any felony having been committed.

"In their presence" is not the only allowable condition. "Immediate knowledge" of a crime is adequate to justify a citizen arrest. They had immediate knowledge of the crime.

You are ignoring the portion of Georgia law that states "immediate knowledge" is an acceptable alterantive.