A hot spot flared up Wednesday morning at the burned out Tecumseh Roadhouse.
Fire crews responded to the scene around 3:30 a.m. The fire was put out within an hour, nobody was hurt.
The Ontario Fire Marshal finished investigating Wednesday afternoon. Some samples have been sent away for more testing.
Tecumseh firefighters responded to the original blaze at the restaurant on Essex County Road 42 around 7:30 p.m. Monday.
Tecumseh OPP are calling it "suspicious" in nature.
Officials say the fire likely started on the second floor of the commercial building.
Police say the restaurant was closed at the time and no one was inside the building.
Damage is pegged at $500,000.
