Lincolnshire Police are warning residents and are looking for information regarding burglars entering houses through unlocked doors.
On December 26, a thief creeped into a house on Chelmsford Street during the day through an unlocked backdoor, stealing a handbag.
The same thing also happened on Christmas Day on Sincil Bank.
Officers are appealing for information regarding either of the above incidents.
Police are also warning residents to be vigilant and lock all unattended windows and doors, even when they are in the house.