New Fairfield Police are investigating catalytic converter thefts.  Police say the exhaust emission control devices from two vans parked at the New Fairfield Senior Center were stolen during the overnight hours of Monday into Tuesday.  The high value of metal in the devices is believed to be a driving force nationwide behind an increase in catalytic converter thefts.  Officials say vehicles with high clearance are common targets because they provide easier access to the devices.  Anyone with information or video footage that may help the investigation in New Fairfield is asked to call the Police Department at 203-312-5701.