Twenty-nine vehicles have been broken into during the last three weeks, with 13 of the incidents being reported this week.
Most of the thefts occurred on Monday night, when cars were targeted in Upper Midvale Road, Rue de Haut in St Lawrence, Duhamel Place, Old Trinity Hill, Richmond Road, Tower Road, Highlands Lane and Bagatelle Road. Car windows were broken to steal the items, which included handbags, purses, iPods and laptops.
Det Con Jeremy House, crime reduction officer for the States police, urged Islanders not to leave valuables in their cars.
