Police are investigating the cause of a suspicious fire that destroyed two houses in Newark.The fire began early Monday morning in an empty home at 763 South 19th Street. It quickly spread to the neighboring house forcing the eight people inside to run billowing smoke and flames. Firefighters spent two hours extinguishing the flames from both homes. Firefighters say the home where the fire began has been deemed unstable and will be torn down.Neighbors say the tenant that was recently evicted from the destroyed home was seen coming and going. A family member of the home?s owner says the fire is no accident. Investigators are calling the fire suspicious.