(AP) —A New Jersey school district has hired an outside law firm to investigate how and why a Jewish student group was erased from the high school yearbook, with the members’ names omitted from the page and their photo replaced with a picture of a group of Muslim students.

East Brunswick Public Schools said the independent review by Brisman Law began Friday and will seek to determine who was responsible, as well as whether it was malicious or a mistake.

“I’m confident the independent counsel investigation will reveal the truth,” Superintendent Victor Valeski said. “They’ve been given complete authority to investigate whatever they need to investigate.”

The superintendent apologized previously for “the hurt, pain and anguish this event has caused our Jewish students” and offered a separate apology to Muslim students.

In a statement, East Brunswick Mayor Brad Cohen called it a “blatant Anti-Semitic act” and said the probe should consider whether it was a hate crime worthy of prosecution. “Hate has no place in East Brunswick and Anti-Semitism will not be tolerated,” he said.

The New Jersey office of the Council on American-Islamic Relations called for a “transparent and fair investigation.” The yearbook incident “has triggered heinous backlash against some Muslim students who had no knowledge on their photo being misused,” spokesperson Aya Elamroussi said in a statement.

The situation came to light Tuesday after about 375 yearbooks were distributed at East Brunswick High.

Valeski said a new photo of the Jewish Student Union was taken this week and will be included, along with the members’ names, in corrected versions of the yearbook that will be distributed next week.

Discipline could be warranted depending on the outcome of the probe, and a corrective plan will be developed for the yearbook, Valeski said.

“There’s absolutely no way it should have happened,” he said. “I believe that this was really a lack of quality control, a lack of oversight.”