A Decatur structure fire is being investigated as suspicious, firefighters said. Crews said they responded at 8:52 p.m. Monday to 825 N. Water St., where they found a fire with light smoke coming from the roof line of the structure. Crews extinguished the flames after entering the front of the building with hand lines. Additional crews pulled the ceiling and extinguished a fire above the ceiling. After the roof was vented, responders said they entered and noted multiple candles. They believe an unattended candle was responsible and added they found evidence of occupancy by people who are homeless. The rear door of the building was unsecured. Buildings on both sides of the fire structure were checked for possible extension. The fire did not spread to either of those buildings.