A man accused of starting a massive fire at Gallery Furniture has been deemed incompetent to stand trial because of a brain tumor.

Robert Gillham, 66, was charged with first-degree arson.

He's accused of setting the four-alarm fire that caused nearly $20 million worth of damage at Gallery Furniture's north Houston warehouse in May 2009. The fire did not spread to the store's main showroom, but the sprinklers inside it went off and caused extensive damage.

Gillham will have to be evaluated every 90 days to determine if he has regained competency.

His next court hearing is July 18.