John L. McCullough, 75, was in extremely critical condition at Vanderbilt University Medical Center.
Police say Vincent R. Harris, 43, banged on the door to McCullough's home at 1:15 a.m. CDT Wednesday. Harris' estranged wife and two sons, ages 4 and 6, were in the home at the time.
When McCullough opened the door, Harris doused him with an accelerant and set him ablaze, police say. The home also caught fire.
Harris fled, McCullough crawled through the front door, and Sheila Harris and the boys escaped unharmed.
Officers said Harris may have left the Nashville area.
They say Sheila Harris had called the Emergency Communications Center about 11:50 p.m. Tuesday night to report that Harris was at the rear of the home, threatening to throw a brick through the window. He fled before officers arrived.
McCullough obtained a court order of protection against Harris earlier in the month, saying that Harris had accused him of poisoning him, that Harris was out of control and repeatedly cursed him.
