Walcott Vows Dismissal of Anyone Sexually Abusing Students Hoping to quell anxiety after three members of the teaching staff were arrested and accused of sexual crimes involving students, Dennis M. Walcott, New York City's schools chancellor, ordered a review of all substantiated cases of misconduct dating back to 2000 on Friday and pledged to remove any teachers who had engaged in sexually inappropriate behavior. In two of the cases, the teacher or teacher's aide had been found to have acted inappropriately with students at previous schools, but had been able to transfer. Education officials acknowledged on Friday that they had failed to notify the principals of the new schools of the earlier accusations. The developments came on a day when angry parents at Public School 174 in Rego Park, Queens, where the most recently arrested teacher worked, confronted Mr. Walcott during a tense two-hour meeting. And while Mr. Walcott tried to assure parents that the safety of their children was of paramount concern, the city's public advocate, Bill de Blasio, said in a letter to the chancellor that the city's overall response had been lacking. "I do not understand how the existence of previous inappropriate conduct does not trigger automatic, ongoing oversight; the absence of such actions by the Department of Education suggests negligent oversight and a failure of accountability," he wrote. Richard J. Condon, the special commissioner of investigation for the school system, said there were 66 substantiated cases involving a sexual allegation in 2011. But that number includes a broad range of cases, including sexual harassment of employees, and the Education Department could not immediately say how many had involved inappropriate behavior with students. On Thursday, Wilbert Cortez, 49, a computer teacher at P.S. 174, was charged with sexually abusing two male students by touching their genitals and buttocks over their clothes. He was released on $50,000 bail on Thursday. He did not respond to a message left with the doorman of his apartment building in Queens on Friday. A lawyer for Mr. Cortez, Donald H. Vogelman, said his client - who, he said, had no criminal record - intended to fight the case in court. "In my experience," Mr. Vogelman said, "if the Department of Education has credible evidence that a teacher is a danger to students, they remove that teacher from the classroom. In the year 2000, Mr. Cortez's case was fully investigated, and a determination was made to put him back in the classroom. The principal at P. S. 174 apparently did not know that Mr. Cortez had been found, in 1999 and 2000, to have slapped the buttocks of two students at another school. Similarly, P. S. 87 on the Upper West Side accepted the transfer of a teacher's aide, Gregory Atkins, 56, unaware that he had been found to have had an inappropriate relationship with a student at another school in 2006, sending a boy gifts that included a jockstrap. In both Mr. Atkins's and Mr. Cortez's cases, the earlier episodes had not been considered criminal in nature at the time. Mr. Atkins was arrested last week on sexual abuse charges; he is accused of inappropriately touching a P.S. 87 student after forcing him to undress. In a letter to parents sent home with students on Friday, Mr. Walcott said that in the future, all principals and the Education Department's human resources staff would be able to see reports on any employee against whom misconduct allegations had been upheld. Mr. Walcott also wrote that the department would review cases dating to 2000: "Thinking prospectively is not enough. That is why my staff will look back at substantiated cases of misconduct and take appropriate action where necessary to ensure the safety of our students. Asked to elaborate on the failure of the department to share information, Matthew Mittenthal, a department spokesman, said, "There is a system in place, but it highlights different kinds of information in different ways." For instance, he said, principals had access to a teacher's service history, rating history and information about a current suspension without pay. He added that principals were encouraged to contact a teacher's prior school and ask questions about performance. But if discipline did not result in a suspension of pay or firing, Mr. Mittenthal added, the hiring principal might not know the teacher's full history. Principals will now have access to such information. Ernest A. Logan, president of the Council of School Supervisors and Administrators, the principals" union, said the union "supports the chancellor for acting to ensure that appropriate action is taken against staff members with a record of sexual misconduct involving children." "A teacher with a proven history of sexual abuse against children," he added, "should never be allowed in a classroom again." In the third arrest, Taleek Brooks, an aide at P. S. 243 in Crown Heights, Brooklyn, was charged last month in federal court with violating child pornography laws. Officials said he had made videos of himself inappropriately touching students, possibly at the school. Mr. Brooks did not have a known history of inappropriate behavior. During the meeting at P. S. 174 on Friday, Mr. Walcott was often interrupted by angry parents. "There was a lot of emotion," said Kevin Rodriguez, 39, the father of a third grader. Leonard Shirman, whose two daughters were both students in Mr. Cortez's computer classes, said that he was not especially satisfied with Mr. Walcott's appearance. "On a lot of questions, he didn't have answers," he said. I'm very surprised that in 2012 we still have breakdowns that allow this to occur. Chris Palmer contributed reporting.