A lengthy investigation into a string of home invasions has led to the arrest of a Fort Gratiot couple.  Members of the St. Clair County Sheriff/Port Huron Police Major Crimes Unit (MCU), the St. Clair County Drug Task Force and detectives from both departments have been conducting the investigation involving break-ins that have taken place in Fort Gratiot, Burtchville and Kimball Townships, along with the north end of the city of Port Huron.  At approximately 6:30 Friday night, the 50 year old man and 42 year old woman were observed breaking into a home on Manchester Drive in Kimball Township and were arrested a short time later.  Two search warrants were then executed in Fort Gratiot Township and suspected stolen property from other home invasions was recovered.  The pair are suspected of committing numerous home invasions in several areas in the county.  Both are being held at the St. Clair County Intervention and Detention Center.  The suspects are expected to be arraigned Monday on several charges, including home invasion and possession of stolen property.