Investigators are trying to figure out if the crimes were committed by a violent armed robber or a serial killer.
Police say they are also looking for an older woman who may have witnessed the most recent killing. That occurred Friday when an Iranian shop keeper was shot to death inside his boutique in Brooklyn. Authorities say two other possible witnesses have been questioned and released.
The other two shootings, from earlier this year, were linked to Friday’s when investigators discovered the same .22-caliber gun had been used in all three.