Fred Roberts, 65, was charged with arson and attempted murder.
On Wednesday, a judge accepted Roberts' plea of not criminally responsible by reason of insanity and signed an order committing him to the Maine Department of Health and Human Services for an indefinite period of time.
According to court records, Roberts poured gasoline inside the Hudson Road home and set it on fire in January because he believed 70-year-old Barbara King wanted to die.
King was forced to jump out of a second story window to escape the flames.
She broke her neck and several ribs and fractured vertebrae in the fall.
Officials said Roberts had suffered head injuries before the incident and was delusional when he set the fire.