Police were searching for the ex-boyfriend of a 23-year-old woman who was fatally shot outside of Brooklyn Bridge Park on Monday night, the NYPD said.

Michelle Marks was gunned down at about 9:30 p.m. after leaving her job at an artisanal pizza restaurant, Fornino, 30 minutes earlier, a police source said.

Marks had just missed the bus when investigators believe she was confronted by her ex, the source said.

Marks, from Crown Heights, was shot in the head and found lying on the sidewalk, police said, where she was pronounced dead.

No arrests had been made as of Tuesday.