Caravan owners in Doncaster are being targeted by burglars waiting to strike when they go on holiday, police said.
A spate of burglaries in the town has been blamed on "a small group who are watching properties with caravans on the drive or in the garden".
"Once they see the caravan has gone, they assume the owners are on holiday and burgle the property," a South Yorkshire Police spokesman said.
The same gang were also believed to be operating in Nottinghamshire, he added.
Officers have released a picture of a man they want to speak to in connection with a recent burglary in Branton, Doncaster.
Det Insp Steve Whittaker said: "We believe this is a small group of people that are targeting houses when residents take their caravans from the drive or garden away for their summer holidays.
"If any members of the public believe they know the identity of the man in the picture, I would urge them to come forward as he may be able to assist in tracing the people responsible for these crimes."
Police are conducting extra patrols and are working closely with officers from Nottinghamshire Police.