Seventeen-year-old Matthew David Voran has pleaded no contest to arson of a dwelling. Investigators say he torched the back porch of his family's home in suburban Callaway last October.
His father, mother and brother were asleep inside the house. The teen's father suffered smoke inhalation and some injuries while fighting the blaze with a fire extinguisher.
Deputies say the teen had threatened his parents in the past and had argued with his father about 90 minutes before the fire was discovered.
The fire did an estimated $10,000 to $20,000 damage to the house.