Motorists are being reminded to lock up their vehicles after car crime has almost doubled in the last two weeks.
There have been 28 offences including number plate thefts and items being taken from vehicles from wallets and purses to workman tools.
Det Insp Justine Jenkins said: “By taking a few small simple steps you can help prevent becoming a victim and reduce the opportunity for thieves to steal your belongings.
“The advice is really clear - make sure you remove all items of value and lock your vehicle when you leave it.
“We have also seen a lot of offences where number plates have been stolen. These can be costly to replace and an inconvenience. You can buy anti-tamper screws for your number plates very cheaply and we highly recommend them.”
Crimes have taken place in Hall Road, Claymore, St Johns Road and Belswains Lane in Hemel Hempstead, New Ground Road in Tring and Langley Hill, Kings Langley.
For more security advice people can visit www.herts.police.uk or call 101.