More than two years before Abel Cedeno fatally stabbed a classmate and wounded another, his mother alerted a teacher that she feared her son was bringing a knife to his Bronx school.

She believed she had reason to worry: He had previously pulled a knife on family members.

But that information was not formally conveyed to the education department through its official incident reporting system, according to the school system’s Special Commissioner of Investigation, which blames an assistant principal for much of the communication breakdown in a report issued Thursday.

The report comes just days after Cedeno was sentenced to 14 years for killing Matthew McCree and seriously wounding Ariane Laboy at the Urban Assembly School for Wildlife Conservation in the Bronx in 2017. The school has since been closed

The incident was the first time in 20 years that a student was killed by a peer inside a school, sparking outcry and debate about bullying, metal detectors, and the city’s broader efforts to move away from strict discipline policies.

Cedeno’s mother left a voicemail for her son’s English teacher in 2014, saying that she found a knife in her son’s backpack and he had been bringing it to school. She worried it might be used for violence, according to the teacher’s report at the time, because Cedeno “has a history of pulling knives on his family.” 

The teacher alerted the school’s assistant principal, Caridad Caro, who was responsible for overseeing discipline issues. The teacher logged the incident in the school’s internal gradebook system, but Caro didn’t tell the school’s principal or other staffers and failed to enter it into the department’s official reporting system, which is required, according to the report. 

The department was “deprived of critical information necessary to monitor [Cedeno’s] conduct and assure the safety of DOE students and staffers,” according to the report.

The next time Cedeno came to school after his mother’s call, Caro asked him to report to her office and searched his backpack herself. She didn’t find a knife. That search, the report found, also violated a department policy because it should have been conducted by a school safety agent. 

The report concludes by recommending that Caro, who now works in a central office, be fired.

“Ms. Caro was immediately reassigned when we were made aware of this allegation, and based on the findings of the investigation, we will start the termination process,” education department spokesman Will Mantell said in a statement.

A principal union spokesman, Craig DiFolco, declined to comment on the report’s findings citing pending civil litigation, but said the union “will provide appropriate representation and vigorously defend the due process rights of our members.” Caro did not immediately respond to a request for comment on Thursday.

It’s not clear whether other former Wildlife staffers are facing investigations from the special commissioner. The report notes that multiple school officials were aware of the mother’s call warning about a knife and that it came up at a cabinet meeting with administrative staff, including the principal. 

Also unclear: What kind of intervention would have happened if the mom’s report of a knife had been logged through the department’s official channels. A spokeswoman for the special commissioner emphasized that the report did not conclude that Caro’s actions had “a direct effect” on the eventual stabbing.

Still, the special commissioner’s report sheds some light on Cedeno’s key defense for the stabbing: that he had been repeatedly bullied and harassed for being gay and was acting in self defense. In the aftermath of the stabbing, some reports surfaced that there was a pattern of bullying at the school, leading one student to attempt suicide.

Yet the report includes interviews with several school officials who met with Cedeno dozens of times and who testified that they were not aware of Cedeno being bullied. 

Christina Veiga contributed reporting