Guernsey Police have warned islanders to be on their guard against walk-in thieves.
Andy Goodall, crime reduction advisor, said there were two recent cases where thieves struck while householders were in the building.
He urged people to lock up when they got home for the evening.
He said: "In both these cases valuables have disappeared overnight and it's invariably due to doors being left unlocked."
Mr Goodall added: "In one case unfortunately wrapped Christmas presents went, so there are people out there who will take advantage of every opportunity if we present that opportunity to them."