WASHINGTON — The longer it takes you to notice your credit cards have been stolen, the more time crooks have to pull off illicit shopping sprees.

It appears some thieves in Montgomery County have figured out how to exploit that: Police are looking for crooks who stole wallets from purses that were left unattended in shopping carts, lifted the credit cards and then returned the wallets.

That happened at least twice last month at a Rockville Pike shopping center. A third woman’s purse was stolen from her car in the shopping center’s parking lot, again with the purse and wallet returned, but the credit cards gone.

Police think they know who’s behind the thefts, and have pictures of a man and woman who reportedly used the stolen cards.

Advice from police to keep wallets secure include:

• Don’t leave purses on the backs of chairs or in shopping carts.
• Keep your purse closed, and as close to your body as possible.
• Carry wallets in an inside pocket or front pants pocket.
• Lock car doors and leave no valuables visible.

Crime Solvers will give up to $10,000 to a tipster with the right information to catch the credit-card thieves. You can call police at either 1-866-411-TIPS (8477) or 240-773-6084.