A brain-damaged man accused of starting a 1996 fire at an Ohio fireworks store that killed nine people has died at a mental health facility.

Todd Hall died March 8 in a behavioral health facility in Athens where he had been getting treatment for the last several years, according to the Lawrence County Prosecutor's Office. He was 43. A cause of death couldn't be immediately confirmed Monday.

Hall, of Proctorville, was 24 when prosecutors say that, as a prank, he threw a lighted cigarette on a shelf crammed with fireworks at the Ohio River Fireworks store in Scottown, about 100 miles southeast of Cincinnati. The blaze on July 3, 1996, killed eight people. A ninth died later. Eleven people were injured. Five of the victims were from Ohio; the four others were from nearby West Virginia.

According to court testimony, Hall had part of his brain removed after suffering a serious injury in a 1987 skateboard accident and had the mental capacity of a 10-year-old. Charged with aggravated arson and nine counts of involuntary manslaughter, he repeatedly was ruled incompetent to stand trial in the years since then.

In recent years, he had shown severe impairments in his ability to control his behavior, regulate his mood and take care of himself and was deemed incapable of living outside a facility, according to the last court-ordered evaluation a few years ago.

Authorities initially thought three friends challenged Hall to set the fire, but they all passed polygraph tests and were never charged. About 40 people were in the store at the time and ran for the exits when fireworks started going off.