Of course this is hearsay like all the other information about this incident. I heard that this Mother and Child were over near Moss Mill Road parked and enjoying the sunset. They saw a neighbor's truck drive by which was returning Louis Alano to the Bowen Ranch. After Louis Alano had been dropped off, Mike Castro and Louis Alano came over to where the Mother and Child were.
Now, I am pretty darn sure that Louis Alano would have recognized the Mother's truck since she is a neighbor. Local vehicles are commonly recognized since there aren't that many people living up there.
So, I think they knew who they were going to confront. Now why would the fact that the Mother and Child were over there bother Mike Castro enough for him to drive over there?
Now, from there I don't know who said what to whom first. But, I highly doubt that the Mother would just start verbally abusing Mike Castro with no provocation in front of her young child (4 years old). Especially when the last time she had seen him, Mike Castro gave her and her son a ride to her home after hiking from the springs.