"We know he's responsible for two, probably many, many more because in the general area, not only Upper Darby, they're getting killed with these thefts," said Supt. Mike Chitwood, Upper Darby Police.
The latest incident happened on Thursday, March 27 around 8:45 p.m.
Authorities say a male suspect went into the Planet Fitness off of State Road and Lansdowne.
The suspect broke a lock off of a man's locker and got away with the victim's wallet. Minutes later, the suspect went to a nearby CVS and Rite Aid pharmacy and purchased $1,200 worth of items.
"At CVS and Rite Aid? What was he buying? That's amazing, people will do anything for some money now a days," said Nick Dolhancryk.
"I can't believe that. I don't wanna put stuff in my locker now," said Angela Geiss.
Police believe it's the same man who broke into a locker at the LA Fitness on West Chester Pike in Havertown a week earlier.
In a separate incident, a group of men are wanted for breaking into cars and taking money, credit cards and checkbooks outside of a Planet Fitness on the 5200 block of Baltimore Pike in Upper Darby.
The suspects were seen riding in a car at the McDonalds across the street buying food. They were also spotted buying gift cards at a Target in Springfield.
Police say one of the suspect's, seen wearing dark clothing, appears to be in his 50s or early 60s.
People go to work, they go work out after they're done working and then these bums come along and steal everything that they work for that day," said Supt. Chitwood.
With the weather getting warmer, some people have the tendency to leave their car windows down.
"Me and my Mom, we're at the McDonalds, we had our windows open and my mom is always leaving stuff in there," said Paul Fisher.
Police urge people not to leave valuables in your car at all. People are also urged to be cautious about leaving items in gym lockers, even those with locks on them.
Meanwhile, anyone with information on the men in the surveillance pictures is being asked to call Upper Darby Police at 610-734-3439.