Police say two officers spotted a man tossing a duffle bag into the trunk of a double-parked Nissan in Inwood just before 8:30 p.m. Saturday.
When officers approached the vehicle, the man who threw the bag ran away.
Police say 26-year-old Joancis Delacruz-Arias remained in the driver's seat and let the officers search the bag.
They found nearly 20 pounds of heroin inside, with a street value of approximately $750,000.
Delacruz-Arias was arrested and charged with first-degree criminal possession of a controlled substance.
Anyone with information about the search for the second person is asked to call Crime Stoppers at 1-800-577-TIPS (8477).