New York City police say they would like ballistics results of the gun used in the Tampa, Florida, killings to see if it matches any unsolved crimes in New York.
24-year-old Howell Emanuel Donaldson was arrested Tuesday by Tampa police in the shooting deaths of four people.
He has been charged with first-degree murder and detained after a tip that he had a gun at a McDonald's restaurant.
They said he used the same gun for all the shootings.
Authorities say the gun was purchased in early October.
Donaldson attended St. John's University in Queens, graduating in January 2017.
Police in New York said he had an arrest in 2014 for a minor crime, but the arrest was sealed.
NYPD Chief of Detectives Robert Boyce said police will go back through cold cases to see whether Donaldson could be linked to any crimes.
Police officials are in contact with Tampa police.