Authorities say officers nabbed Isaiah Malailua after police dogs found explosive residue in his bag at a train station.
The 21-year-old is from California. It is still unclear how he got the NYPD body armor.
NYPD say they are working with Chicago Police in the investigation.
Malailua is charged with unlawful use of a weapon.
----------
* More local news
* Send us a news tip
* Download the abc7NY app for breaking news alerts