Someone forged my signature on a check. Why did the bank pay it?

http://www.finfaqs.com/2358/someone-forged-my-signature-on-a-check-why-did-the-bank-pay-it

Even if your bank or credit union knows you and your signature very well, there are too many checks going through the U.S. financial system every day for these institutions to process them manually: They rely on automated systems that process checks based on the routing number codes on the bottom of the check.

If you think you have been the victim of a forged check, you'll need to review your statements and fight the fraud. You'll also need to review the agreement you signed when you set up your account with your bank or credit union, and find out which laws govern forgeries in the state in which you live. These laws are based on the concept of "prompt notification".

But you should know that you may not have a long time to do this: In many cases, you have only have 30 days from the statement date to alert your financial institution.

Get in the habit of reviewing your statements as soon as they arrive in the mail or in your email inbox.