The suspect has been identified as Aleem Reed.
In all three incidents, the victims were contacted in reference to an expensive watch posted for sale on the website.
The victims met the suspect at prearranged locations, where they were then robbed at gunpoint.
The first incident occurred August 8, on the 1400 block of Jefferson Street. Shortly after the victim arrived, Reed demanded the Rolex watch and fled on foot.
The second incident happened August 15, on the 1900 block of North Gratz Street.
While an unidentified male, posing as the buyer, glanced at the watch, Reed approached the pair and announced a robbery. The suspect took the watch along with the victim's cell phone before fleeing the scene.
"Basically, the same M.O. happened every time, they would contact someone on Craigslist in reference to purchasing a high end piece of jewelry or a watch," said Lt. Evers.The most recent incident happened August 17, also on the 1900 block of North Gratz Street.
The victim met with an unknown male, claiming to be a buyer. Shortly after, the suspect approached and demanded the watch. When the victim refused, Reed shot the man in the leg, took the watch, and fled.
No word on the victim's identities.
Craigslist says it had over 573 million postings on its North American website last year, so the odds are miniscule that some are going to be associated with crimes.
And while it may be a wonderful, useful tool for buying or sell stuff on the internet, police are issuing warnings to internet users.
"Be very, very mindful of your surroundings. Do as much homework as you can on that potential buyer or seller," Lt. Evers said. "I mean, make sure you go to a place that you feel safe and bring someone with you. Make sure someone knows where you are, and go to a very, very public place to make that transaction."
Officials suggest some place like 30th Street Station in Philadelphia, or a police district, but never in some isolated street or location you are not familiar with.
Police are also looking for help locating Aleem Reed, and are asking anyone with information to contact police or call 911.