NASHVILLE, Tenn. -- It seems a new law to crack down on copper thefts in Tennessee isn't putting thieves out of business as police hoped.

Video: Thieves Hocking Copper On Internet

Last month a law went into effect that requires all metal dealers in Tennessee to not only register with the state, but sellers have to also leave a thumbprint and show photo identification.

In addition, companies no longer are allowed to buy from people with felony theft and burglary convictions.

As a result, police for a while saw a big drop in the number of people stealing air-condition coils and catalytic converters.

"We have people popping up, acting as middle men," said Metro police Lt. Danny Driskell.

Dealers and some thieves are heading to Craigslist and other Web sites to do business. Search for "copper" on the site, and there are lists of people looking to buy and sell metals, offering cash on the spot for scraps.

However, part of the law requires that most dealers pay their customers by check or voucher.

Police said not only is what the thieves doing illegal, they are also hurting businesses that are following the law.

Authorities have busted several of the online dealers through undercover buys, but as more are popping up, they'll be ready to put a dent in this dirty work.

"We're going to arrest them, and prosecute them to the max of the law," said Driskell.

Metro police said the Tennessee Bureau of Investigation is working with them and other counties by setting up stings to bust the illegal dealers.