Police say the same suspect robbed a Boost Mobile on Southern Boulevard in Crotona on Monday and a Metro PCS store on White Plains Road on Friday.
A store clerk at a cellphone store on Tremont Avenue says the man seen the surveillance videos is the same person who robbed him weeks ago.
"He just came inside the store and he started, like, talking to us like a customer," the clerk, who did not want to be identified, told CBS2's Cory James.
Before he knew it, he says the man went from asking to look at phones to demanding the clerk hand over cash.
"'Give me all your money, otherwise I am going to stab you.' He was repeating again and again, 'I'm going to stab you, I'm going to stab you, give me all your money,'" the clerk said.
The clerk did just that, fearing what would happen. He says the suspect had two knives in his hands pointed toward the clerk's stomach.
NYPD investigators say the serial thief has hit a total of four stores since July.
Police say he's managed to get away with three phones and more than $10,000 in cash.
The clerk at the Tremont Avenue store gave the suspect $200 from his own wallet.
"I did that to, like, try to save myself," he said.
One customer is hoping fliers posted outside of the places the knife-wielding man hit will lead to an arrest.
She feels if he is bold enough to do it in broad daylight, he is capable of doing it in front of anyone at anytime.
"That's scary, especially because I have young kids that goes in the store with me to pay my bill," she said. "I hope they lock him up and send him to jail."
Authorities say no one was injured in any of the robberies.
Police are also offering a $2,500 reward to anyone who can help them arrest the suspect.
Anyone with information is asked to call the NYPD's Crime Stoppers hotline at 1-800-577-TIPS (8477), or for Spanish, 1-888-57-PISTA (74782). You can also submit a tip via their website or on Twitter, @NYPDTips. All calls are kept confidential.
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