The serial killer is the so-called "Dating Game killer."
He's on death row in California, but he lived in New York City for several years.
Police have linked him to two Manhattan murders, and they are now worried he may have killed more people here.
Some estimate the "dating game" killer may have killed more than 100 women and girls.
SLIDESHOW: VIEW THE PHOTOS
INTERACTION: DO YOU RECOGNIZE ANYONE?
These new pictures released by the NYPD may or may not be his victims, but police believe all 226 photos were taken in New York by this killer.
Rodney Alcala, now 66, lured his victims with a click of his camera. He asked them to pose for pictures.
He was dubbed the "dating game killer" because of an appearance as a bachelor on that show.
Alcala is on death row in California for five west coast murders.
He was convicted of strangling four women and a 12 year old girl.
These newly released photos were found in a storage locker that he rented in Seattle up until his 1979 arrest.
Detectives believe some of the photos were taken in New York City.
If you recognize any of the individuals in the photographs, some of whom may have been photographed by Alcala while he was residing in New York in 1970-71 and again in 1977, please notify the NYPD's Crimestoppers' Hotline at 1-800-577-TIPS.