LILBURN, Ga. -- A woman ordered a chicken sandwich and then robbed a Subway restaurant in Lilburn.

Subway surveillance video showed a woman pull out $20 to pay for her sandwich and a pistol to rob the place.

Just one good fingerprint is all Lilburn police crime scene investigators were hoping for when they surveyed the money drawer. It's what police said the Subway suspect grabbed when she robbed the Subway on Rockbridge Road on Tuesday.

"I just open register and she showed me the gun and tell me don't shout please," said Amisty Ferdose.

Ferdose was the frightened cashier who stared down the barrel of the gun. Subway's surveillance cameras caught the entire robbery. It showed a woman casually walk in, order a chicken teriyaki sandwich and she even had a casual conversation with another employee.

Tanvira Momin said, "She was asking me how my day going on and am I ready for Thanksgiving."

The suspect sounded nice and polite but she was armed and dangerous.

The woman grabbed the cash, stuffed it in her purse along with her gun and considered grabbing her sandwich, then decided to leave it as she casually walked out of the restaurant.

Lilburn CSI is hoping she left fingerprints on that sandwich bag.

"Super glue -- you take a fish tank, heat it up, if there are viable prints they'll show up they'll be burned into the material of the plastic," said Officer Matt Price.

Police are counting on forensic evidence and the surveillance video to catch the crook. Police said the woman left the restaurant in a 1996 or '97 sky blue Honda Civic that's missing the right front hubcap.