A team of purse snatchers messed with the wrong grandmother.
That's because their target, Nancy Kelly, is a veteran deputy sheriff in Cook County, Illinois.
The showdown took place Friday evening inside an Oak Lawn sandwich shop.
The 61-year-old grandmother of three left her dining booth briefly.
When she returned, Kelly noticed a woman sitting in the booth.
After confronting her, Kelly looked inside her purse and noticed the wallet missing.
She chased the woman into the parking lot, and grabbed her by the collar.
Identifying herself as a sheriff's deputy, Kelly demanded the wallet back.
The culprit handed it over, but with all cash and credit cards missing.
Kelly then grabbed the thief's purse, where she suspected the stolen items were.
Suddenly, two associates of the wallet snatcher showed up, and the group wrestled over the culprit's purse.
That's when Kelly grabbed the woman's hair and began punching her in the face.
All this as the suspected thief was trying to bite Kelly's hand.
Bystanders had called for help, and police arrived.
One of the three suspects was immediately arrested.
Two others, including the original wallet snatcher, had driven off.