A car was stolen from outside a house in Abbots Close, Kettering, sometime overnight between Tuesday, October 29, and Wednesday, October 30, after thieves reached through a letterbox to grab the keys.
The car, a red Ford Focus, was last seen parked outside the property at about 10pm on Tuesday and had been stolen by 6.20am the following morning when the owner got up.
It is believed the offenders used an implement to reach through the letterbox and take the car keys from within the house.
Officers would like to speak to anyone who may have witnessed this incident or who may have any information regarding it.
People are also being reminded to make sure they keep any valuables, including car keys, out of site at all times.
Witnesses should phone Northamptonshire Police on 101. Alternatively, information can be given anonymously to Crimestoppers on 0800 555 111.