Police say the 35-year-old man, whose name has not been released, was stabbed in the chest Saturday night.
A San Antonio police spokesman tells the San Antonio Express-News that the teen was in custody Sunday and faces a murder charge. As a juvenile, his name is not being released.
Police say that as the teen's mother and her boyfriend argued, items were thrown and furniture was knocked over.
A spokeswoman for Child Protective Services says two other children -- ages 7 and 10 -- were in the home at the time and were placed in the care of relatives.
