The LAPD has busted an alleged bike theft ring after an NBC4 I-Team investigation caught thieves in the act.

The I-Team exposed the ring, which police say may have brokered the sale of thousands of stolen bicycles, during an undercover investigation into the growing problem of bike theft in Southern California.

In some parts of the LA area, like North Hollywood and Santa Monica, bicycle theft is up more than 200 percent in the last four years.

More: 5 Things You Don't Know About Bike Theft | How to Protect Your Bike | How to Get a Stolen Bike Back

To see how it happens, the I- Team locked a bicycle at the bike racks July 17 at the North Hollywood Metro Station – a frequent target of thieves.

Just four hours later, a man in a ball cap approached the bike, crouched down, and within 16 seconds clipped the cable lock and rode off on the bike, a Giant Revel mountain bike, which retails for about $525 brand new.

In about 16 seconds, the man easily snips the coil cable lock. He removes it, then takes the bike off the rack.

Then he rides away on his newly purloined bicycle.

When the I-Team showed its video to the LAPD, they confirmed that the thief was no amateur.

“He’s a professional,” LAPD Capt. Peter Whittingham said. “He knows what he’s looking for.”

The I-Team had secretly installed a GPS tracking device on the bike, which led NBC4 to a house in Sun Valley. The I-Team flew NewsChopper 4 over the house, and saw a large stash of bikes covered by tents and tarps in the back yard.

The LAPD then moved in on the house, seized the bikes, and arrested Juan Luis Torales.

Detectives say Torales admitted to buying and selling bikes he thought might be stolen. He was charged with one count of "receiving stolen property," but pleaded not guilty.

The LAPD says there’s reason to believe Torales has been buying and selling a lot of stolen bikes.

“I would say at the minimum hundreds, if not thousands,” Whittingham told NBC4.

Police tell NBC4 they're still searching for the man caught on camera stealing our bike (pictured below). Anyone with tips is asked to call the Los Angeles Police Department.