Local authorities are looking for a man suspected of committing at least 21 locker break-ins at area gyms throughout the Southland.

According to Simi Police Detective Keith Eisenhour, the fitness gym burglaries have taken place in Santa Barbara, Los Angeles, Orange and Riverside counties, but Ventura County has been hit hardest with 10 break-ins.

Of those 10, four took place in Simi and six in Thousand Oaks.

Police have been working on the case since July 2008. Eisenhour, who works in the department's financial crimes unit, said the most recent burglary occurred in Palmdale on April 2.

"Prior to that, the last one in Ventura County was in Simi on March 9," Eisenhour said.

The detective could not release the names of the fitness centers hit by the suspect but said they are major commercial gyms like 24 Hour Fitness and Gold's Gym.

The subject is described as a white adult male, 30 to 35 years of age, with short, dark brown hair and a clean-shaven face. He is about 5 feet 8 inches to 5 feet 10 inches tall and weights 165 to 175 pounds.

Based on video surveillance, police know the subject makes repeated trips to the men's locker room, waiting until no one is around to make his move, Eisenhour said.

The thief removes the locks from the lockers by either cutting or otherwise defeating the locking mechanism.

He then steals wallets and the credit cards inside them.

The subject has used the credit cards at numerous retailers, including Best Buy, Macy's, Office Max, Staples and Bed, Bath & Beyond, netting merchandise valued at $1,500 to $3,000 per victim.

"You're looking at between $30,000 and $60,000, and those are the ones we know about," said Eisenhour, adding that the thief has likely committed 30 to 40 break-ins.

Since the last break-in, Eisenhour has received three more phone calls in connection to the case, including one from a Santa Monica resident saying his locker was also robbed.

All involved law enforcement agencies are working in conjunction with area gyms to identify, apprehend and prosecute the thief.

Anyone with information as to the identity of the subject is asked to contact the Simi Valley Police Department at (805) 5836950.