MILWAUKEE (CBSNewYork/AP) — An original Pablo Picasso print worth up to an estimated $50,000 was stolen from a downtown Milwaukee art gallery.

Picasso only did 30 of the prints and signed each with a green crayon in the lower right corner.

Appraiser Bill DeLind says someone could have walked in the unlocked door unnoticed because he and his business partner were upstairs. The gallery does not have surveillance cameras. He says he hopes a camera across the street captured the thief.

“This is intentional,” DeLind said. “We didn’t want to attract someone who was just looking at values. Somebody either knew what they were doing or just got lucky.”

Delind says he called police and then nearby art appraisers, museums and art galleries around the country in case the print turns up.

Milwaukee police confirm a report was filed for the stolen painting.

(© Copyright 2017 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)