According to police, a Fairfield child living in a home on Overture Lane with his mom and stepdad, just couldn't take seeing his mom hurt anymore.
He stepped in with a knife to defend her with deadly results.
FOX40 spoke to one neighbor who asked us to conceal her name and face.
"So I saw the kid before, I always seen them before, going to school, but I never heard any arguments or noise to make me think that something's going on. And so that's ... we're really shocked by what's happened, and now we heard that somebody's died. It's, really sad," she said.
Shock was thick in the air in a Fairfield neighborhood near Solano Community College, a place where one resident left his home in a body bag.
Police say as the fighting between his mom and stepdad intensified Saturday night into Sunday morning, a young boy between the ages of 10 and 12 grabbed a knife from the kitchen.
To save his mom's life, investigators indicate the child stabbed his stepfather -- a 45-year-old man who'd been arrested earlier this year on domestic violence charges.
Perhaps no one inside the Overture Lane house realized how serious the wounds inflicted really were.
The boy's mother called for help about 6 a.m. Sunday, telling 911 dispatchers she couldn't wake her husband up.
To protect the child, the man's name is being withheld at this time.
Police say they offer counseling, housing and other resources to all families involved in domestic violence cases in their city.
Twenty percent of those cases involve children under 12 living in the home.
"You're dealing with very delicate victims ... victims that don't think they can get out of that situation by themselves, or they have children or they're in a relationship that they're afraid to leave. So we have to utilize as much help as we can sometimes to help convince a victim they're a victim," said Fairfield Officer Cleo Mayoral.
Based on their review of this case, detectives and the district attorney have not pursued any arrests at this time.
The investigation is ongoing.