Police say a spate of recent burglaries may have been carried out by crooks who target homes as the nights get longer.
There have been seven burglaries in the Berkhamsted area since mid-October.
These include a break-in at Station Road overnight from Friday to Saturday, November 3, where a black Audi was stolen.
Jewellery was stolen from a home in Covert Road between 6pm and midnight on Wednesday, October 10, after thieves broke the locks on a back door.
More jewellery was taken from a Bridgewater Road home between Sunday, October 14, and Thursday, October 18, after a window was forced open.
Det Insp Justine Jenkins said: “At this time of year when the nights are getting darker earlier, it is very easy for criminals to see if a property is empty.
“I’d remind people to ensure they leave a light on to give the impression someone is in as we know that burglars tend to avoid a property if they think there’s someone inside.”
She said a team of detectives is working on the burglary cases and reminded people to ring 999 as soon as they see any suspicious behaviour.
Nothing was stolen during break-ins at Ivy House Lane between 2.15pm and 5.30pm on Friday, November 2, and at Kilfillan Gardens between 6pm and 7.10pm on Sunday, November 4.
Burglars targeted homes in Castle Hill Close between 12.10pm and 7.15pm on Sunday, October 28, and in The Green between noon on Tuesday, October 2, and noon the next day – but again escaped with nothing.
Police spokesman Hannah Williams said this may have been because they were looking for jewellery that they did not find or because they were disturbed.
Burglary prevention tips include making sure all windows and doors are closed and locked before leaving the house or going to bed.
Also shut and lock all garden gates, lock away garden tools that could be used to break into your home and use timer switches on lamps to make your home look lived-in if you are out after dark.