The owner of the Post Road Diner in Norwalk says police are investigating the fifth grease theft within the past year at his business. Police have advised him to move his surveillance camera closer to the grease trap to catch the suspects if they return. The most recent incident happened on Monday.Authorities say thieves typically steal the oil from restaurants to sell to companies that recycle it.Norwalk police say grease thefts on the riseNorwalk police investigating grease thefts