Postal employees entrusted with destroying old stamps managed to steal at least $500,000 of them in the nation's biggest such theft because no one was watching to make sure they carried out their task, officials say.

The disappearance came to light last month when Postal Service officials said they had recovered hundreds of thousands of dollars in postage in the homes of two local postal employees. Mailbags containing $15,000 to $20,000 more were found dumped in a ravine.No charges have been filed, but 11 postal employees have been fired and three suspended.