The development came after the Anti-Defamation League of New York and New Jersey criticized her for antisemitic social-media posts made in 2011 that have resurfaced. The ADL said they echoed “classic antisemitic tropes,” calling her “money-hungry Jews” post “indefensible.”

“Woo! Promoted to the upstairs office today! Working alongside these rich Jewish peeps,” she wrote in one post. “Money hungry Jews smh.”

The ADL said the controversy warrants a direct response from both the appointee and the mayor-elect. “We appreciate Da Costa has relationships with members of the Jewish community, but her posts require immediate explanation,” it said.

The Jewish watchdog also raised questions about how Mamdani’s team handles background screening and what standards will apply going forward, noting that the appointment office will play a central role in evaluating future hires.

In her resignation, Da Costa “apologized and expressed my deep regret for my past statements,” adding that “these statements are not indicative of who I am.”

She noted that she is the “mother of Jewish children” and that she feels “a profound sense of sadness and remorse at the harm these words have caused.”

In a statement, Mamdani said “Catherine expressed her deep remorse over her past statements and tendered her resignation, and I accepted.”