A gang has got away with three prestigious cars by sneaking into homes while families relaxed and finding ignition keys.
After the three offences around Belper in five days, residents are being urged to step up basic security to prevent repeats.
People were reminded to lock all outer doors, even if they are in, and ensure keys are out of the view of anybody looking through windows.
Detective sergeant Sarah Yendley said:”We would ask people to keep doors and windows locked.
“In all these cases, the families were in when the cars were taken from outside their homes. They didn’t realise they had gone until some time later.”
Two of the car thefts took place in Belper and one in Kilburn. The first was reported on November 5 and the last on the 10th.
The last offence took place on Blackden Close between 6.30pm and 9.40pm when a grey BMW X5 was taken. A couple and their children were indoors when offenders opened an unlocked rear door and searched the kitchen, finding the keys in a purse.
Police believe the same team is to blame for the three offences. Sometimes the cars get new registration numbers, some are stripped down and some can be exported.