As we reported here, mad Mary Ann Holder, 36, was furious that her boyfriend Russell Lamb had decided to end their affair and go back to his wife.
So after calling him to a meeting near their home in Greensboro, NC, she fired a number of shots she eventually managed to blast him in the shoulder, as he ran away.
She went on to shoot her sons Robert Dylan Smith 17, and Zachary Smith, 14, in the head, instantly killing the eldest, before firing at Robert's girlfriend, Makayla Woods, 15, and killing her niece, Hannaleigh Suttles, eight.
Then she turned the gun on herself.
Zachary had originally survived the blast to the head, but last night he passed away, Guilford County Sheriff, BJ Barnes confirmed.
Holder's nephew and her older son's girlfriend remain in critical condition.
Investigators are still trying to unravel the violent chain of events to understand why Holder took out her rage on children. She left notes taking responsibility for the shootings and apologizing for the pain she was causing, Sheriff Barnes added.
The notes also indicate Holder was angry about how her relationship with Lamb came to an end.