Now, his mother is facing charges.
VIDEO: Fairfield police say 10-year-old boy killed abusive stepfather
Fairfield resident Carissa Aldrich, 38, was arraigned in Solano County Court on Friday on charges of involuntary manslaughter, child endangerment and destruction of evidence. She pleaded not guilty.
Out on bail, Aldrich had little to say. "I just can't talk at this time, thank you," she said.
In late October, police responded to Aldrich's home on the 700 block of Overture Lane. Police said Aldrich called for help, saying she couldn't wake her husband, Tim.
First responders seemed confused when they entered the home. "There's a lot of blood on the ground. It's a very unusual scene. I'm not sure what is going on yet," they reported when they got to the scene.
Initially, Fairfield police said Aldrich's 10-year-old son stabbed her husband in an effort to protect her.
"It sounds like he was truly afraid for his mom's safety at that time,' Officer Kathryn McCormick said.
There was a documented history of domestic violence allegations. Charges in 2013 and 2014 were dropped due to insufficient evidence.
Nearly three weeks after the stabbing, police arrested Aldrich on involuntary manslaughter, child endangerment and destruction of evidence charges.
"Once we looked at it further on in our investigation, we realized that due to her actions and inactions, she was culpable for part of this crime," Lt. Rob Lenke said.
Neighbor Jim Phillips said he was not surprised. "The story was fishy from the get go. The child is very young, he's a very small person," he said.
Aldrich's son is with Child Protective Services. At her arraignment, she requested a public defender.
Her next court appearance is in January.