Police released surveillance video from Lilly's Market in Woodlynne Sunday night.
Police say the suspect approaches the cashier, appears to be reaching for money, but then pulls a silver handgun and robs the place.
But what he does next is even more disturbing.
"He robs the place, but then asks the clerk - not asks - tells the clerk to go in the bathroom with him and he exposes himself. Fortunately it didn't go any further than that," said Jason Loughlin, Camden County Prosecutor's Office.
The suspect tried to force the woman to perform a sex act, but she acted like she didn't understand, and he fled.
"Obviously it was a terrifying act for her, and this is the type of person we don't want out there," said Loughlin.
During the robbery the suspect worked alone, but investigators say he had an accomplice during four other robberies in the Woodlynne-Camden area over the past month.
One of the robberies to place at the Express Mart on Woodlynne Avenue. One of the victims, who does not want to be identified, faced the barrel of a gun.
"I thought he was buying something. I think he came a couple of days before too," he said.
The Camden County Prosecutor's office say the duo is also responsible for a couple of robberies on Mt. Ephraim Avenue.
Officials say a store was hit on the 3000 block, and again the two thieves wanted cash.
Detectives want the suspect off the street before his crime escalates even further.
"We are really hoping that reaching out to the public will be a difference maker," said Loughlin.