All fourteen of the robberies, dating back to January, happened while in transit in Manhattan and the Bronx.
In each incident the suspect approached the victims on subway trains and either displays a knife or simulates a firearm.
The suspect then demands the victim's property and bank card PIN numbers.
Some of the victims have suffered minor injuries.
Investigators say he struck three times this month.
On August 5, he robbed a 22-year-old woman riding the J line at Nassau and Fulton Streets.
Four days later, he robbed a 27-year-old woman riding the C train at St. Nicholas Avenue and West 163 Street.
Last Friday, the bandit struck again. He held up a 35-year-old man while riding the F line at 169th Street and Hillside Avenue.
In all three of these cases, he used a knife to threatened his victim.
Anyone with information on this case is asked to call the New York City Police Department's Crime Stoppers Hotline at 1-800-577-TIPS.
You can also submit tips by logging onto the Crime stoppers web site at www.nypdcrimestoppers.com or texting tips to 274637 (crimes) then enter TIP577.
NEW YORK AND TRI-STATE AREA NEWS