The suspect has been identified as 43-year-old William Gibbs who is also known as Michael Johnson.
He's 5'6" tall, 210lbs, bald, with a stocky build, and was last seen wearing a white t-shirt.
Police say he's also wanted in a 5th attack that happened Wednesday afternoon.
The suspect is accused of approaching the 85-year-old man from behind, grabbing him by the neck, and throwing him to the ground at the Central Park West/West 72nd Street Station around 1:50 p.m.
The suspect then reached into the victim's pocket and removed an undetermined amount of money from his wallet and then fled the station in an unknown direction.
Detectives say he always attacks from behind, clubbing and choking his victims.
Four of the victims have been elderly men, one of whom suffered a stroke.
The first incident happened on August 13 around 7:30 a.m. at Broadway and West 28th Street. The suspect approached an elderly male from behind as he entered the N train subway entrance and choked him from behind, removing the victim's wallet. The suspect fled on foot in unknown direction. That victim sustained a stroke as a result of this incident.
Then, on August 16 at approximately 3:45 p.m. at 1178 Broadway (Urban Living), the suspect followed an elderly male into an elevator in a commercial establishment and choked him from behind, removing currency and a cell phone. The suspect fled on foot in unknown direction. There were no injuries as a result of this incident.
The suspect also struck on August 18 at Broadway and West 28th Street and August 21 at 8th Avenue and West 23rd Street. Both of those crimes fit the same M.O. as the others.
Anyone with information in regards to these incidents is asked to call Crime Stoppers at (800) 577-TIPS (8477).
The public can also submit their tips by logging onto Crimestoppers website and at WWW.NYPDCRIMESTOPPERS.COM or by texting their tips to CRIMES (274637), and then entering TIP577.