NYPD Commissioner Raymond Kelly said authorities believe the suspect, Salvatore Perrone of Staten Island, would have kept on killing if he hadn't been caught, The Wall Street Journal reported.
"I think it's reasonable to assume that he was just going to continue doing this and by arresting him we saved lives," Kelly said. "We know that he went to other locations and asked questions that indicated ... he very well may have been planning to come back."
The commissioner said Perrone is alleged to have made statements implicating himself and that police have recovered a sawed-off .22-caliber rifle belonging to the suspect that tests show was used in all three shooting deaths.
The rifle, which had Perrone's fingerprints on it, was found in a duffel bag in the closet of the suspect's girlfriend's Brooklyn apartment. A man carrying a duffel bag captured on surveillance cameras in the area had prompted police to dub the man "John Doe Duffel Bag" prior to Perrone's arrest.
The girlfriend was not considered an accomplice at this time, Kelly said.
While all three of the victims were of Middle Eastern descent, a motive for the shootings had not been determined, Kelly said.
Isaac Kadare, Mohammed Gebeli and Rahmatollah Vahidipour, who were all in their 50s, were killed in July, August and Friday at small shops that didn't have security cameras and were within a 5-mile radius in Brooklyn, police said.
Rewards of $22,000 were offered in each of the homicides.