Salt Lake fire investigators are trying to determine the cause of a two-alarm fire Sunday that caused $75,000 damage to the Adolescent Residential Treatment and Education Center, 54 S. Seventh East.

Fire officials said Monday the blaze, which started in a rear porch room, was of suspicious origin. The blaze fire confined to the room, the attic and the roof. Firemen said another suspicious fire occurred at the center in the summer.