The incident happened on February 5 inside the Family Dollar Store on the 700 block of West Lehigh Avenue.
The suspect was caught on surveillance walking into the store at 4:45 p.m.
He browsed around, hiding some items inside his coat.
As he tried to walk out without paying for the merchandise, a security guard confronted him at the front door.
That's when the suspect can be seen reaching into his coat pocket and pulling out a syringe.
He verbally threatened the store employees before fleeing the store with a bottle of Tide laundry detergent still in his jacket.
No injuries were reported during this robbery.
Police describe the suspect as a black male, 5'9" tall with a dark complexion and facial hair. He was wearing a green pullover windbreaker, blue jeans, carrying a green bag, and armed with a syringe.
If you see this suspect do not approach him, contact 911 immediately.
To submit to police, dial 215.686.TIPS (8477) or text a tip to PPD TIP (773847).