(KMOV) -- News 4 is tracking another crime trend that police say is happening all over the area while people are working out.
Investigators say they think one man behind locker-room thefts in Arnold, Maryland Heights and St. Peters.
One victim told police he had a combo lock, and had even made sure it was secured on the locker, but that didn't stop the thief from taking advantage.
"It's kind of messed up someone did that,” said Julio Rao, a member of a gym.
People at the Gold's Gym in St. Peters are shocked to hear about a recent theft.
Police say a man snuck inside and removed a wallet and credit cards.
"The victim told us he did have a lock on his locker and when he came back the lock was gone,” said Officer Melissa Doss, with St. Peters police.
The thief acted fast, heading to a Target not far away.
"He bought an iPad at one area of the store, went up to the cash register and tried to purchase a very large gift card."
It was an $800 gift card, which police say is just the thing criminals want.
“It can't be tracked or tracking it is very difficult, so a lot of times they sell it or trade it with other criminals."
But in this case, it sent up a red-flag. When asked for ID, the suspect walked out of the store.
Police tell News 4, thieves target gyms, knowing people leave their stuff unattended.
"Just got to be more careful now I guess,” Rao said.
That’s a wise idea, police say, if you want a stress free workout.