(Vancouver, WA) -- A Vancouver, Washington dad is facing charges after allegedly assaulting his 5-month-old son. Police arrested 36-year-old Aaron Thornewood Tuesday on charges of second-degree domestic violence child assault. He pleaded not guilty to the charge in court yesterday. Authorities say his son needed brain surgery to stop the bleeding and to remove a blood clot. Thornewood says his son received the injury from his two other sons while they were arguing over a toy.